Blackpool strengthened their position in the Championship play-off places as Angel Martinez's first goal for the club gave them victory over Leeds.
The midfielder pounced on a loose ball to sink a spirited United side that finished with 10 men after Darren O'Dea was sent off for a second yellow card.
The home side were a more consistent threat throughout, although Leeds had their chances, largely from set-pieces.
The win leaves Blackpool four points ahead of seventh-placed Middlesbrough.
With only two games left to play, Ian Holloway's side are firm favourites to secure a place in the play-offs that would give them a chance of an instant return to the Premier League.
They were made to work hard for this win, though, by a hard-working and well-organised Leeds side, who came into the game off the back of a confidence-boosting 4-1 home win over Peterborough on Saturday.
Blackpool had the better of the first half, with Matt Phillips clipping a shot into the side-netting and Lomano Lua Lua thwarted by a superb save from United keeper Andy Lonergan, although Ross McCormack had a penalty shout waved away after he tumbled after getting the better of Stephen Crainey.
The visitors grew as a threat after the break and Robert Snodgrass had Matthew Gilks at full-stretch from a 67th-minute free-kick before substitute Luciano Becchio headed over from Adam Clayton's cross.
However, Blackpool won the game when Tom Ince failed to fully control a cross and Martinez was on hand to stab home.
Leeds' quest for an equaliser was ended when O'Dea saw red following a second bookable offence.
Blackpool boss Ian Holloway:
"I'm absolutely delighted, I'm on top of the world. That was as tough a game as you'll ever have, as tense a game as you'll ever have and I thought Leeds came here and made it really difficult.
"We showed a lot of belief when we needed to. I'm very, very pleased with everybody concerned.
"I don't care about Middlesbrough's result. It's about us, we've got Burnley next. We have to win. If we win one of our last two games we're guaranteed it."
Leeds boss Neil Warnock:
"I couldn't fault the effort, the effort was fantastic. It's just a matter of being patient really.
"I thought it was a penalty [for the McCormack incident] The ref said 'there was something not quite right' - I don't know what that means.
"We are lacking in certain areas and we can't do anything about that until the summer, so roll on the summer."