Nottingham Forest are now eight games without a win after a 4-1 defeat at Elland Road.
An excellent first half by Forest was marred by a late sending off for Chris Cohen after he was shown a dubious red card for a challenge in which he clearly got the ball.
After a goalless first half, Leeds took advantage of the extra man and scored four in the second half, with Forest, in spite of remaining positive throughout, only managing to get one back.
Leeds had an early chance when Bradley Johnson ran clear on goal but, after Lee Camp had blocked the ball, the referee pulled the game back for a free kick to Leeds, giving them another chance to score. But Max Gradel sent the ball over the crossbar from just outside the D.
And Forest had a free kick three minutes later when Paul Anderson was brought down by George McCartney just inside the D but Lewis McGugan's effort went into the wall.
Barry Bannan came close for Leeds with a powerful effort from long range and the ball bounced dangerously in front of Camp but he did well to gather it up quickly.
Forest threatened when the ball was played in from the left to Radi Majewski who bent the ball towards the far corner of the net but it was deflected out for a corner.
With Forest now dominating the play, they came close again when Joel Lynch sent the ball right across the face of goal where Marcus Tudgay slid in at the far post, but couldn't make good enough contact with the ball and it went wide.
A break from Leeds gave them a chance but Robert Snodgrass sent the ball straight into the arms of Camp.
There was a delay in play while Anderson received treatment after picked up a hard knock in the ribs and he still looked in pain when the match got back under way.
But he was unable to carry on, being replaced by Garath McCleary on the half hour mark.
Forest came close again when Majewski put in a superb cross to Tudgay who saw his shot from in front of goal cleared off the line.
Forest were unfairly down to ten men when Chris Cohen was sent off for a challenge on McCartney. But he clearly got the ball and it could have been the reaction of the Leeds players and managers that influenced the decision.
Forestkept their composure and continue to threaten the Leeds goal and after McGugan had his free kick punched away by Kasper Schmeichel a shot from McCleary forced the Leeds keeper to dive to his right to make a stoppage time save.
Leeds started the half well and Jonathan Howson put them in front six minutes in after a good break down the right. He picked up the cross from Eric Lichaj and from inside the 6-yard box, controlled the ball well to send it past Camp and into the far corner.
Forest reacted positively by bringing on Nathan Tyson in place of Kris Boyd.
But Forest were two behind in the 58th minute from a Leeds corner. The ball came in to Leigh Bromby whose header came off the far post and back out to Luciano Beccio who was in a perfect position to head in past Camp.
Snodgrass came close to a third after his effort from the right corner of the penalty area had Camp beaten but the ball hit the top corner of the far post.
Forest were back in the game after a superb goal from substitute McCleary who ran into the box and sent the ball curling past Schmeichel and into the top corner of the net.
And Schmeichel did well to put the ball over the crossbar after Wes Morgan got on the end of Majewski's corner.
But Leeds increased their lead again after a battle for the ball between Snodgrass and Morgan and the Forest defender cleared the ball, but only as far as Gradel, who turned and sent the ball flying into the net from inside the D.
Forest remained positive with their next substitution which saw Robert Earnshaw return from injury to replace Tudgay.
And they came close to getting one back when Luke Chambers knocked the ball into the box and it came off a Leeds player to Tyson who sent it flying towards goal, but just inches wide of the near post.
But the game was put out of Forest's reach when Leeds got their fourth and Gradel his second after Camp initially parried Becchio's effort away but it fell for Gradel who slotted the ball into the back of the net.
Nottingham Forest: Camp(C), Gunter, Morgan, Chambers, Lynch, Cohen, McGugan, Majewski, Anderson(McCleary 30min), Tudgay(Earnshaw 80min), Boyd(Tyson 54min)
Subs not used: Darlow(GK), Bennett, McGoldrick, Adebola,
Bookings: Cohen RED CARD 36min, Tudgay 45min, Boyd 45+3min, Tyson 68min, Morgan 73min, McCleary 77min
Scorer: McCleary 65min
Leeds United: Schmeichel, Lichaj, O'Brien, Bromby, McCartney, Johnson(Kilkenny 88min), Howson, Snodgrass, Bannan,Gradel, Becchio(Somma 90+2)
Subs not used: Higgs, Naylor, Livermore, Watt, McCormack
Bookings: Bromby 68min
Scorers: Howson 51min, Becchio 58min, Gradel 73min, 87min
Referee: M Halsey