Manager Chris Wilder says the Championship title is in Sheffield United's sights after they beat Ipswich 2-0 to all but secure a Premier League return after a 12-year absence.
With Leeds playing Aston Villa tomorrow, the automatic promotion places have yet to be finalised.
Barring an improbable swing, however, United's superior goal difference looks certain to see them secure a return to the top flight for the first time since 2007.
Scott Hogan (24) scored with a deft touch from O'Connell's ball in to ease the tension among the home supporters.
The second goal came in the 71st minute when John Fleck's corner was met by a close-range header from Jack O'Connell, sparking joyous scenes among the home support.
There were jubilant scenes on the field at the full-time whistle, and Wilder said: "I'll let you guys talk about where you think we're going to be next year.
"We still have a game to play but we're going to try and win the Championship. That's how our mindset is. Who says we can't?
"We've taken an unbelievably massive stride today but the game's not done yet. It's got to be an unbelievable swing between now and next Sunday.
"Hopefully we've done it, which is an incredible feeling for everybody connected with the club.
"It's been a long week – possibly the longest week of my life.
"Fourteen points over seven games at the back end of the season with one defeat in 13 at the business end of the season and people still question whether we are going to fall away.
"We've just kept our heads down and answered it in the right way, which is on the green bit.
"I thought they were absolutely outstanding. I thought the way we played and the way we started, we probably should have taken it from one to two a little bit quicker.
"We possibly should have taken it from two to three but we dominated the game. They had a few passes in midfield but we defended well and were ambitious in our approach.
"The clock never shifted. It's just a fabulous experience. We've taken the knocks and we've come roaring back."
Ipswich are already down and battled manfully until the deadlock was broken.
Boss Paul Lambert said: "Congratulations to Sheffield United. They're nearly, nearly there. They're a very good side. I think they're the best team we've played.
"What I did say to the lads is 'remember that atmosphere because we could have that next year'.
"We never capitulated, which was good. All credit to the team, they kept going.
"I can't fault the players for their effort because we stayed in the game as long as we could. The team kept on battling and they gave it everything.
"It was always going to be tough and it was a difficult game for us. They've beaten a lot better teams than us here so it's no disgrace."