Proschwitz missed a penalty in the closing stages and although Nicky Maynard levelled up proceedings for Cardiff in stoppage time, Watford's loss at home to Leeds United meant that Hull gained promotion.
You can find out how the match unfolded with our minute-by-minute updates.
12.02pmAfternoon all. So, after a long slog of 45 matches, it's come down to 90 minutes as far Hull City are concerned. They face Cardiff City at the KC Stadium and come the final whistle will hope that they have been promoted to the Premier League along with their Welsh visitors. It promises to be a big afternoon ahead.
12.03pmRight, before we get into all the statistics and pre-match talk, the team news from the KC Stadium is just beginning to filter through. Let's start with the home side...
12.07pmSo, Jay Simpson will lead the line for the Tigers, while George Boyd playing in an advanced midfield role. Elsewhere, former Manchester United youngster Robbie Brady will start on the left side of midfield, which also includes David Meyler.
12.08pmAnd here is how Cardiff will start the encounter...
12.15pmWell, there is a few changes to that Cardiff starting lineup. Most notably, the experienced Craig Bellamy has dropped out and has been replaced by Etien Velikonja. Craig Noone, Craig Conway and Jordan Mutch have also been included in the midfield. Even with the alterations, it still looks like a strong Cardiff side.
12.19pmFor such an important fixture, it would be to say that Hull do not go into this clash in the best form. To be honest, they should have secured automatic promotion already - having gone three matches without a win or a goal! A win last week over Barnsley would have made this game meaningless, but they slumped to a 2-0 defeat at Oakwell.
12.23pmThe man charged with the task of ending Hull's recent problems in front of goal today is Jay Simpson. The former Arsenal trainee has been called up by Steve Bruce to replace Matty Fryatt as a lone striker. Simpson may not be a prolific goalscorer, but he has shown in the past that he is capable of finding the net. If he scores today, it's unlikely that he will have bagged a bigger goal during his career.
12.27pmRight, let's take a couple of minutes to see what Bruce has been saying about this encounter. The Hull boss is in no doubt as to how big this match is for his side:
"It's a huge game for everyone concerned and it reminds me of a play-off final. It's a big opportunity," he told BBC Radio Humberside. "Let's bring it on and really enjoy the occasion. I hope it's a bouncing KC Stadium.
"In my experience I think they'll come here wanting to spoil our party. We couldn't have asked for a more difficult game but we've got to overcome that."
12.29pmAnd here is a little bit more from Bruce: "It's all about us and how we perform and I'd rather be where we are than where Watford are.
"It'll be just as difficult for them because they've been playing without expectation in the last few games. They've had a wonderful couple of results but their previous six or seven were disappointing. It's all to play for but whatever they do if we win then we're up."
12.33pmUnfortunately for Hull, Cardiff manager Malky Mackay has insisted that his side will not take things easy today - they have come to win. He told Wales Online: "We have to respect the League. This match is live on television and the outcome of matches on Sunday will mean £100m and more to one team.
"We have been top of the Championship for more than five months and we will do all we can to finish on a high."
12.37pmOf course, today in the Championship is not all about the automatic promotion battle. There are still playoff places to contest, as well as two spots to fill where relegation to League One is concerned. You can keep up to date with all the goals courtesy of Sports Mole's Pascal Lemesre here.
12.41pmThere's a great atmosphere inside the KC Stadium. One would imagine that the Hull supporters are full of nerves, but at the moment they are not showing any. Here come the players to a great reception. Not long now until we are off and running.
1 minGAME ON! Hosting Hull, kicking from right to left, get this £100m fixture started. Big 90 minutes ahead.
3 minHalf an opening for the hosts early on as the ball breaks loose inside the area for Ahmed Elmohamady. His effort is deflected over for a corner, which ends when Robbie Brady sees his drilled cross cleared to safety. Positive start by the home side.
6 minHaving been on the back foot during the opening stages, Cardiff have now started to venture into the Hull half. A cross from Noone is headed clear by Paul McShane, but it is a sign that the Bluebirds have come here to get something from this fixture.
10 minDISALLOWED GOAL! The ball is in the Cardiff net, but it's been ruled out correctly for offside. It actually cannons into the goal of George Boyd's backside, but he was beyond the last Cardiff defender when Meyler struck the initial shot. Hull look a yard or two quicker at the moment.
15 minA quick break by Hull and their full-back Liam Rosenior goes unrewarded because as the ball is finally worked to Elmohamady wide on the right, his cross is easily collected by Cardiff goalkeeper David Marshall. The hosts had just two players in the box there. For a side that needs a goal, you'd have thought they would commit one or two more players further forward.
19 minCHANCE! Almost the opener for Cardiff and Conway. The winger is allowed to cut in from the left onto his favoured right foot. Having weighed up his options, the Scot went for goal and saw his effort from the edge of the area skid a yard wide of the target. That's a really good strike and I'm not sure David Stockdale would have got there had it been on target. A warning for Hull.
22 minA quick update from Vicarage Road and there have been no goals, which I'm sure you Hull fans will be glad to hear. However, reports coming through have suggested that Watford should have had a penalty for a foul on Jonathan Hogg. It wasn't given though and it remains 0-0. Hull are going up automatically as it stands.
27 minFor all the pressure that Hull have applied, they haven't called Marshall in the Cardiff net into any telling action. To be honest, you can see why they have struggled to score goals of late. Apart from Boyd and Elmohamady, no other players are getting up to support lone striker Simpson.
31 minBOOKING! The first caution of the game goes the way of Cardiff and their captain Andrew Taylor. Having needlessly pushed over Elmohamady on the right byline, the defender then tries to argue his case. A combination of the two offences results in him being rightly booked.
33 minCHANCE! A big opportunity for Hull is wasted by Brady. Boyd picks out the attacker on the edge of the area, but despite the fact that he has time and space, he goes for an instant shot which flies over the crossbar. The Irish international needed more composure there.
36 minThere has been a long stoppage in play down at Watford because their goalkeeper Jonathan Bond is down with a serious injury. He's just been stretchered off and that match is now 14 minutes behind this one. If this game doesn't end in a Hull win, it's going to be a nervy, late conclusion to the Championship season.
39 minCHANCE! Conway went close moments ago for Cardiff, but Jordan Mutch has just gone even nearer to putting the Welsh wide in front. The former Watford midfielder tries his luck from 25 yards out, but the ball brushes the upright as it is deflected wide. Yet another warning for Hull, who won't keep getting so lucky.
41 minDown at Watford, Bond has now been stretchered off. Reports have suggested that it is a neck injury for the keeper. It doesn't sound good, as Rory Smith from The Times has just written on Twitter: "Bond's name chanted and given standing ovation by crowd. On stretcher, oxygen mask on. Horrible. Hope it's better than it looks."
44 minA massive cheer goes up around the KC Stadium because LEEDS HAVE SCORED AT WATFORD! They lead 1-0 thanks to a goal Dominic Poleon, who was involved in the incident that saw Bond have to go off. It's a big advantage for Hull now, but it is worth remembering that the match at Vicarage Road is around 15 minutes behind this one.
45 minSUBSTITUTION: A change for Hull at the end of this half because Simpson is injured and cannot continue. He is replaced by German target man Nick Proschwitz as the board goes up to tell us that there is two minutes of stoppage time. The fans are still cheering that Leeds goal!
1.37pmSo, as it stands, Hull are heading for the Premier League. It's just as well that Leeds are winning because the Tigers haven't really looked like scoring against Cardiff. If Watford were to equalise, it will probably start to get very nervy around the KC Stadium. This automatic promotion race is by no means over.
1.38pmThat injury to Watford keeper Bond means that they are now playing a staggering 16 minutes of stoppage time at Vicarage Road. While we wait for the Hull and Cardiff players to return, let's keep up to date with events at that match shall we? Why not!
1.41pmWhat a time to turn our attention elsewhere because Watford have drawn level and it is a cracking curling effort from Abdi - do Watford score boring tap-ins?! The Hull players will probably know this and their half-time team talk may be a little different now. As it stands, it's still advantage Hull, but another goal for Watford will put them in command. Likewise, if Cardiff were to take the lead, the Hornets would move up to second - it's that close!
1.44pmWhat must those Hull players be thinking right now? They went into the break well in control of this automatic promotion battle, but as it stands they are holding on by the skin of their teeth. It's a big team talk that Bruce will be giving. How will his team react? And how will the crowd at the KC Stadium react because they have been brilliant so far.
45 minRight, let's go back to the KC Stadium. The players are back on the pitch and Cardiff have made a change - Fraizer Campbell is coming on for Velikonja. He was part of the Hull side that got promoted via the playoffs in 2008 - what a story that would be if he denies them promotion five years later. A big 45 minutes ahead!
46 minBy the way, it's now half-time down at Watford. There were no further goals so the score remains at 1-1.
51 minWouldn't you just know it! Four minutes into his return and Campbell has scored a massive goal against his old club. He finds himself with so much time and space inside the area and a player of Campbell's quality was never go to miss that. He was jeered when he came on, so had no hesitation in celebrating. Silence falls overs the KC Stadium, apart from a contingent of Cardiff supporters. As it stands, Watford are going up automatically.
53 minCHANCE! That simply has to go in for Hull and Proschwitz. The Big German has struggled to settle in on Humberside and he did nothing to help his cause with a bad miss. Brady flicks the ball into his path and looks as though he has an easy tap-in. Somehow though the ball flies into the side netting, despite some of the crowd thinking that he had scored. What a reply that would have been.
59 minHull are back in business! Having missed a golden chance four minutes ago, Proschwitz steps up to make amends. Stephen Quinn whips over a cross from the left for the striker, who gets in front of his marker. His finish is a scruffy one, but Hull won't care. They are now going up automatically, as it stands. Meanwhile, Watford are back underway against Leeds.
64 minOh my word! What a few minutes we have seen at the KC Stadium. Hull now lead thanks the unlikely Paul McShane, who gets across his marker to volley in a corner by Brady. If it stays this way, Hull are heading back to the Premier League. It's in their hands, but there is still a lot of football to be played.
67 minWhat a difference a goal makes, hey?! Hull are now the dominant force and are knocking the ball around the pitch with real confidence. Surely one more goal will secure their promotion. Incidentally, while Hull were celebrating that second goal, Cardiff brought on striker Rudy Gestede in place of midfielder Kim.
70 minSAVE! Lovely footwork inside the area opens up a chance for Brady. He's on his weaker right foot, but still gets away a powerful shot. However, Marshall is equal to it and is able to parry clear the danger. Hull are buzzing at the moment.
75 minGestede has done well since he came for Cardiff. He gives the Bluebirds a physical presence and is forming a decent partnership with Campbell. It's something that Hull will need to be wary of because another goal for Cardiff could spell disaster.
77 minSignificant news from Vicarage Road as Watford striker Troy Deeney has been given his second yellow card of the match and is off for an early bath. He's been among the goals recently so that is a big blow for Watford. It's all going Hull's way at the moment, although as we've seen already today, it can all change in a matter of seconds.
80 minBOOKING! It's a deserved caution for Cardiff defender Ben Nugent, who hacks down Proschwitz on the halfway line. It was by no means deliberate, but it's a foul nonetheless and out comes the yellow card.
84 minSUBSTITUTION: A nice moment for Cardiff as Nicky Maynard, who thought that he would be out for the season with a knee injury, will play the final six minutes as he comes on to replace Noone. Cardiff now have three strikers on the pitch.
88 minSUBSTITUTION: It's Hull's turn to make a switch as the impressive Brady is given a breather for the final few minutes. On in his place comes Egyptian midfielder Ahmed Fathi to shore things up.
90 minA second (stupid) yellow card of the encounter for Cardiff skipper Taylor. He's off and although he is not happy, he can have no complaints. Meanwhile, just four minutes of stoppage time is all that separates Hull and the Premier League. Can they hold on?
90+2 minWow! Nugent nudges Meyler over inside the area and a penalty is given. Some Hull fans think it is the final whistle and invade the pitch. It's not, and once they are cleared, Proschwitz will take the spot kick.
90+5 minNo is no madder sport in the world than football - I don't care what anyone says! Proschwitz has a penalty saved at one end and then Cardiff win one at the other with their very next attack. Substitute Maynard calmly rolls the ball in and all of a sudden the fingernails are being bitten at the KC Stadium. A goal now for Watford will see them promoted at Hull's expense. Madness!
2.47pmThe fans invade, but the celebrations are muted. They now have to wait for the Watford game to finish, which should do so within the next five minutes or so. You can follow updates from that clash here.