Match ends, Middlesbrough 0, Leeds United 1.
Leeds United moved back to within four points of Championship leaders West Bromwich Albion as Mateusz Klich's strike earned victory over lowly Middlesbrough at the Riverside.
Klich guided a fine shot in off the far post in first-half injury time moments after Pablo Hernandez's low effort came back off the upright.
Boro, who have now lost three in a row and are winless in nine league games since beating Preston North End on New Year's Day, showed decent resolve and had their moments, the best of which saw Marcus Tavernier's curled shot hit the top of the bar after the break.
But Leeds showed the greater fluency and quality in an often frenetic match and created the better chances throughout, with Patrick Bamford, Stuart Dallas and Hernandez all denied by impressive Boro keeper Aynsley Pears on United's way to a third consecutive win.
As impressive as Pears was, Leeds should have added to their goal tally in a victory which sees them remain five points ahead of Fulham, who moved back up to third with a dramatic late win over Swansea City.
Bamford was involved in nearly all of Leeds' best opportunities and he should have put them ahead despite a promising start by the hosts.
The former Boro striker headed meekly at Pears from Luke Ayling's cross, but was unlucky with a clever near-post flicked effort that went just wide soon after and also forced Pears to make another save from a well-struck shot.
Boro matched their opponents' tempo but struggled to find clear openings, although one lovely move almost created a one-on-one chance for Ashley Fletcher, who did manage to tee up Lewis Wing for a shot that went just wide.
The game's decisive moment came seconds after the first 45 minutes were up when Leeds broke and worked the ball to Bamford. His composure set up Hernandez and the Spaniard remained calm after seeing his shot hit the post to eventually find Klich for a tidy finish from the edge of the box.
The second-half response by Jonathan Woodgate's side was admirable, with midfielder George Saville's stinging shot forcing a brilliant save from keeper Kiko Casilla and Tavernier bending a shot on to the bar after great approach play and a fine lay-off by Hayden Coulson.
But Leeds, even without the influential Kalvin Phillips, always looked the more potent in attack and although Boro remain one place outside the relegation zone, defeat means they are now level on points with third from bottom Wigan Athletic who beat Reading 3-0.
Middlesbrough boss Jonathan Woodgate told BBC Tees:
"It was a lot better than the last two games, that's for sure. I thought we matched them for large parts and if we play with that intensity, we'll pick up a lot more wins.
"I'm very disappointed with the goal. Twenty seconds of the first half left - we shouldn't be playing square passes.
"You see the game out and go in 0-0. Leeds can be lethal at times, but we need to do better with that.
"The composure on the ball, the final pass wasn't good enough at times. We were pressing and chasing them down but when you get into possession you need to be cooler."
Leeds boss Marcelo Bielsa:
"The team fought a lot and were very aggressive. We attacked better in the first than second half.
"The team protected the result. We played well in different moments of the match. The team didn't lose their calm and fought. In general we managed the situations well.
"Maybe in some moments in the second half Middlesbrough created some problems but in general we had three more chances than them. There was a lot of fight in the match.
"We resolved well the absence of Kalvin Phillips. We were compact and tough to play."
- 18MoukoudiBooked at 82mins
- 3FriendSubstituted forJohnsonat 63'minutes
- 8ClaytonBooked at 90mins
- 22SavilleBooked at 10minsSubstituted forNmechaat 67'minutes
- 11FletcherSubstituted forAssombalongaat 72'minutes
- 17Hélder Costa
- 19HernándezSubstituted forShackletonat 73'minutes
- Gavin Ward
- Shots on Target
Second Half ends, Middlesbrough 0, Leeds United 1.
Foul by Patrick Bamford (Leeds United).
Ryan Shotton (Middlesbrough) wins a free kick in the defensive half.
Attempt missed. Patrick Bamford (Leeds United) left footed shot from the right side of the box is high and wide to the left. Assisted by Mateusz Klich following a corner.
Corner, Leeds United. Conceded by Marvin Johnson.
Foul by Stuart Dallas (Leeds United).
Hayden Coulson (Middlesbrough) wins a free kick in the defensive half.
Adam Clayton (Middlesbrough) is shown the yellow card for a bad foul.
Jack Harrison (Leeds United) wins a free kick on the left wing.
Foul by Adam Clayton (Middlesbrough).
Attempt saved. Marcus Tavernier (Middlesbrough) left footed shot from outside the box is saved in the bottom right corner. Assisted by Lukas Nmecha.
Attempt blocked. Lewis Wing (Middlesbrough) right footed shot from outside the box is blocked.
Foul by Jamie Shackleton (Leeds United).
Hayden Coulson (Middlesbrough) wins a free kick in the attacking half.
Offside, Leeds United. Gaetano Berardi tries a through ball, but Patrick Bamford is caught offside.
Harold Moukoudi (Middlesbrough) is shown the yellow card for a bad foul.
Hélder Costa (Leeds United) wins a free kick in the attacking half.
Foul by Harold Moukoudi (Middlesbrough).
Attempt missed. Jack Harrison (Leeds United) left footed shot from the left side of the box is close, but misses to the left. Assisted by Stuart Dallas following a fast break.