Brighton's European hopes took a huge hit after a late Dominic Calvert-Lewin strike earned Leeds a 1-0 win in their final home game of the season.
The Seagulls needed to win at Elland Road to ensure seventh place, but the England striker capitalised on errors to score his 14th Premier League goal of the year.
Jan Paul van Hecke's poor attempted pass back for Bart Verbruggen - who was well out of his area - was easily intercepted by Calvert-Lewin. With the goal open, it was then a slotted finish from the Leeds man in the sixth minute of added time.
It was Leeds' only shot on target and the perfect way for Daniel Farke's side to finish their home campaign after their Premier League status was secured last week.
Brighton will feel it was a game they should have won, having had 19 shots and eight on target. The majority of those shots (13) came in an improved second half, having never really got going in the opening 45 minutes.
"The biggest difference is they were lucky and we didn't have the luck in our hands today," Brighton boss Fabian Hurzeler told Your Site. "We weren't ruthless enough, we defended quite well and it's an unlucky loss.
"But we have to accept it, to analyse it and we have to go on and prepare well for the last game."
They did not work Karl Darlow until the 43rd minute as the Leeds goalkeeper made a fingertip save to keep out Pascal Gross's swerving effort. Immediately after, Verbruggen was needed to stop a Lewis' Dunk clearance from sneaking in.
But the Seagulls peppered the Leeds area after the break. Ethan Ampadu was needed to block a Danny Welbeck shot in the pick of the chances, while the hosts continued to offer their own warnings at the other end.
There was another injury concern for Leeds, though as Anton Stach was stretchered off in the second half. He had attempted to carry on but a heavily bloodied foot saw him eventually come off and any potential inclusion in Germany's World Cup squad was thrown into doubt.
Brighton remain in seventh place, two points behind Bournemouth - who have a game in hand - and one ahead of , who twice came from behind to draw against Crystal Palace. , and sit in ninth on 51 points.
It means the race for Europe will go down to the final day, with right now enough for European football after Manchester City won the FA Cup on Saturday.
Brighton boss Fabian Hurzeler to Your Site: "We controlled the game and had plenty of chances. We should have won the game but in the end, that's football and it's painful.
"We have to face this adversity. We faced a lot of adversity this season and we've overcome it and we'll try to go all in for the final game.
"We played better in the second half. We enjoyed it more, we attacked with more desire. In the second half, there was more life.
"I was pleased with the performance. I don't see many teams have that many chances against this team here so we have to stay positive. Although it's a big disappointment for us and a painful loss, we'll go on."
Leeds goalscorer Dominic Calvert-Lewin to Your Site: "It's a great feeling. I think for everyone involved, all our families are here for the final home game, so it's a great afternoon.
"Arguably they were the better side today. They had the most chances and probably should have been in front, but sometimes football's like that.
"You just keep believing you're going to get the next one and thankfully today I was able to put it in the net."
Leeds boss Daniel Farke to Your Site: "Today was a really difficult game. We had to defend, but we stayed in the game. We defended with spirit, mentality and togetherness.
"If you stay awake and believe in yourself, then even in such a game sometimes you have the one chance to win it."
