Leeds took full advantage of slips by their promotion rivals with a 1-0 win over Reading.
Pablo Hernandez hit the winner in the second half to leave United five points clear of third-placed Fulham.
The visitors had successfully contained Leeds during a disciplined first-half defensive display.
But the Yorkshireman cranked up the pressure at the start of the second half and deservedly hit the front when Hernandez coolly finished on 57 minutes.
The hosts had set a good early pace with Helder Costa dragging an effort wide from a narrow angle after four minutes.
Luke Ayling picked up a yellow card on 10 minutes after he hacked down Pele following a Reading counter attack.
Patrick Bamford failed to get on the end of Jack Harrison's cross, before Kalvin Phillips scuffed an effort at the keeper from just outside the box on 16 minutes.
It was the best United could muster up in the opening 25 minutes as the visitors continued to frustrate with organised defending.
George Puscas forced Kiko Casilla into a save with a long-range effort after Stuart Dallas was caught in possession on 26 minutes.
Phillips and Costa needed treatment for injuries as the first half began to lose rhythm, with Phillips subbed on 37 minutes after failing to run it off.
Hernandez fluffed a shot well wide while under pressure from a defender on 39 minutes and Costa had a shot blocked for a corner after a brilliant last-ditch tackle by Liam Moore two minutes before the break.
Ayling volleyed a powerful effort narrowly over, before Gjanni Alioski had a shot saved by Rafael Cabral as Leeds stepped it up on the stroke of half-time.
Mateusz Klich was a yard wide of the target after he robbed Pele of the ball on the edge of the box seconds after the restart and Costa lashed another effort wide on 51 minutes after Klich had seen shot blocked in front of goal by his own man.
Bamford fired a tame shot at Cabral on the turn a minute as Leeds cranked up the pressure.
And the dominance was finally rewarded when Hernandez guided an effort into the top corner after a rebound fell kindly.
Ben White had a shot blocked to safety on 63 minutes after it hit Bamford, before Puscas was off target at the other end.
Cabral acrobatically beat away an Hernandez free-kick on 80 minutes before Bamford lashed a wild effort wide with four minutes to go, but Leeds were indebted to Casilla in the final minute as he spread his body well to keep out Puscas in stoppage time and secure the points.
