The second half was a tense affair, but with 10 minutes remaining, Sone Aluko fired home from six yards to book Hull a place in tomorrow's draw.
Read below to see how the action unfolded at the KC Stadium.
Hello, and welcome to Sports Mole's live coverage of the match between Hull City and Trencin in the third qualifying round of the Europa League.
For the first time in the club's history, Hull City and the KC Stadium play host to a European fixture. It's probably an occasion that many of their supporters didn't feel was possible 10 years ago. But here we are, as the Tigers look to progress through to the playoff round of the Europa League.
Last week's first leg in Slovakia ended goalless. On paper, Hull were expected to open up an advantage, but their hosts more than matched them for long periods. That said, Hull should have at least netted an away goal on the night through Tom Huddlestone, but after seeing his spot kick saved by the goalkeeper, he blazed the rebound over the crossbar. It was a shocking miss, and he will be hoping that it doesn't cost his team by the end of this evening.
We've got just over 20 minutes remaining until kick off in Hull. Let me bring you full details of the two teams.
HULL CITY XI: McGregor, Bruce, Chester, Davies, Elmohamady, Brady, Huddlestone, Snodgrass, Livermore, Sagbo, Long
HULL CITY SUBSTITUTES: Harper, Rosenior, McShane, Meyler, Quinn, Ince, Aluko
Hull boss Steve Bruce has made three alterations to the team that drew 0-0 last Thursday. Out go David Meyler, Liam Rosenior and Sone Aluko, and they have been replaced by Robert Snodgrass, Robbie Brady and Yannick Sagbo
TRENCIN XI: Volesak, Ramon, Klescik, Cogley, Hajrandinovic, Misak, Holubek, Lobotka, Simon, Kubik, Malec
TRENCIN SUBSTITUTES: Semrinec, Mondek, Rundic, Skovajsa, Baris, Opatovsky
This was the scene at the KC Stadium a little while ago. It's a sell-out crowd this evening, so expect those empty seats to be filled when we get underway in just over five minutes time.
The two teams are making their way out onto the well-prepared pitch in Hull. We will have kickoff for you in just a few minutes.
We are underway at the KC Stadium
GOAL! Hull City 0-1 Trencin (Tomas Malec)
It's a disastrous start for Hull City! Steve Bruce's instructions would have been to avoid conceding an away goal, and within two minutes of kickoff, that's exactly what they have done. Malec received the ball in the penalty area before showing terrific composure in driving the ball past Allan McGregor from 14 yards.
Hull respond by winning a corner but it comes to nothing. There's a nervy atmosphere inside the KC Stadium - the home faithful weren't expecting this.
Robbie Brady has come back into the side after missing the first leg through injury, and it has to be said, he looks a bit rusty. He lost possession in the build-up to Trencin's goal and he's just done the same again before conceding a free kick. From the set piece, a shot was fired at Allan McGregor but the Scot was equal to it. The home side just haven't got going.
Again, Trencin come forward through Haris Hajrandinovic, but his driven strike from range just evades the target. That shot brought a nervous oosh from the Hull support. They know that another goal for Trencin leaves this game a long way out of their reach.
That's better from Hull, who create a chance for Yannick Sagbo, but the powerful striker's shot was well blocked by a defender. There were ambitious calls for a handball, but it was never going to be given.
Hull are beginning to enjoy more possession, but the visitors are not being shy in throwing men forward to try to score a second away goal. The Tigers need to be extremely careful - they are having the game taken to them.
It should be said that Trencin are a few matches into their domestic campaign, so that might be the main reason for them looking a lot sharper than the Premier League outfit. Still, you'd expect Hull to be dealing with them a little better than this. They look sluggish.
CHANCE! Hull burst forward through Yannick Sagbo and Robert Snodgrass, but after the ball found its way to Shane Long, the Irishman scuffed the ball straight at the goalkeeper before doing the same with the rebound.
GOAL! Hull City 1-1 Trencin (Elmohamady)
Hull have the equaliser and Ahmed Elmohamady is the man who has got on the score sheet. Robbie Brady, who was in danger of being hauled off after a disappointing first 25 minutes, provided a cross from the flank for Elmohamady to head home at the back post, despite the best efforts of Milos Volesak.
It's fair to say that Hull needed that! They had been struggling to show any kind of quality in the final third, but hopefully, that goal can act as the catalyst for a couple more. Still plenty of work to do, though.
The home side have spent the last few minutes trying to ensure that they keep hold of the ball to prevent Trencin hitting straight back. At this stage of the game, it's a sensible tactic, because if Hull can get to the break with this scoreline, Steve Bruce can make the necessary alterations for the second half.
CHANCE! How has Shane Long missed that! A corner was swung in for the Irishman but after meeting the ball cleanly, his header from three yards was kept out by Milos Volesak. It's been one of those evenings for the former West Bromwich Albion man.
BOOKING! Long's frustration boils over and he enters the referee's notebook for dissent. He needs to regain his composure.
A foul committed against Shane Long is met with ironic cheers and Hull have an opportunity to send a free kick into the penalty area. However, they choose to take it short and they are unable to create anything from it.
There will be two minutes of added-on time.
HALF TIME: Hull City 1-1 Trencin
The half-time whistle goes at the KC Stadium and Hull have reached the break on level terms with Trencin. The Slovakian side stunned their hosts with an early away goal but the Tigers have equalised through Ahmed Elmohamady. They are going to need to score in the second half, though, to have any chance of reaching the next round.
Two other British sides feature at this stage of the competition, and like Hull, they haven't had it their own way. St Johnstone have already bowed out of the tournament after losing 3-2 on aggregate to Spartak Trnava while Aberdeen are as good as out after falling 3-0 behind on aggregate to Real Sociedad.
The two teams are beginning to emerge from the changing rooms. It's a big 45 minutes for Steve Bruce's boys! This match can't go to extra time now, so the result will be decided in the second half.
We are back underway.
Both sides have had a bit of joy in the opening exchanges of the second half, but neither team have managed to get a shot away. At least Hull have made it through the first minute without conceding...
CHANCE! I will keep my mouth shut - Trencin very nearly scored their second away goal there. Haris Hajradinovic held onto possession in the penalty area before seeing his shot deflected agonisingly wide for a corner.
SUBSTITUTION! Steve Bruce makes his first change of the evening, bringing on Liam Rosenior to replace Robbie Brady, who had been making his first appearance for a number of weeks.
CHANCE! Rosenior very nearly makes an immediate impact but his volley on the bounce drifts just wide of the post. He's not known for his goalscoring prowess, but that was close!
We have moved through the hour mark at the KC Stadium and Hull have 30 minutes to try to register another goal. You would have thought that the introduction of Thomas Ince can't be far away.
BOOKING! Jakub Holubek has been cautioned by the referee for a cynical foul on Shane Long. It's a deserved yellow card. Steve Bruce has taken notice of my advice and decided to introduce Thomas Ince for Alex Bruce.
Hull are having the majority of possession now, but they aren't doing too much with it. That needs to change or else their venture into Europe is going to be a short one.
The home supporters are trying to rally their team on, but as of yet, it's having little effect. They've got no momentum on the ball or quality in the final third to suggest that they are going to find a winner.
SUBSTITUTION! Steve Bruce makes his final alteration of the evening, bringing on Sone Aluko for Shane Long.
SHOT! Tom Huddlestone lets fly from distance but his left-footed strike from 25 yards was always rising and it clears the crossbar. 14 minutes remaining and time is running out.
GOAL! Hull City 2-1 Trencin (Aluko)
Hull take the lead! Boy, did they need that. Thomas Ince supplied the ball into the area for Sone Aluko, who wasted no time in volleying the ball into the roof of the net. Now then, can they hang on to this lead?!
The Hull supporters are in full voice now, but this match is far from over. Another goal from Trencin and they will be going through to tomorrow's draw. The Slovakian outfit have definitely upped the pace over the past few minutes.
Trencin are trying to make their final change as we near added-on time. They've gone a little quiet over the past few minutes, but this might just be the calm before the storm...
There will be five minutes of added-on time.
Trencin have a free kick 25 yards from goal. This is dangerous territory for Hull City...
SHOT! Jakub Holubek steps up to take the set piece but the ball drifts marginally over Allan McGregor's crossbar, clipping the top of the net as it went into the stand.
FULL TIME: Hull City 2-1 Trencin
Hull have done it! They have qualified for the playoff round of the Europa League after a gutsy 2-1 victory over Trencin. The Tigers were poor at times, but the introduction of Sone Aluko has proven crucial and the 25-year-old is the hero this evening.
The draw for the playoff round will take place tomorrow lunchtime. The potential opponents for the Premier League side are unknown at this stage, but given that it's their first effort in Europe, they may end up being vulnerable to facing a top side. We shall wait and see...
On that note, I will bring Sports Mole's coverage of this match to a close. Thank you for joining us this evening, and let's hope that this is the first of many involving Hull competing in Europe this season. Goodbye for now.