Match ends, Middlesbrough 3, Leeds United 0.
Middlesbrough closed to within a point of Championship leaders Brighton after beating Leeds United to secure a fifth straight league win.
David Nugent fired Boro in front from close range after only 121 seconds for his third goal in four games.
Leeds defender Giuseppe Bellusci then produced a diving header to divert George Friend's cross into his own net.
Diego Fabbrini slotted in Boro's third after Leeds' Mirco Antenucci saw an effort ruled out for offside.
Boro's victory was their seventh in a row in all competitions but was only their second over Leeds in 12 meetings at the Riverside.
Leeds' hold over Boro on Teesside was under threat in only the third minute when Nugent chested down Christian Stuani's right-wing cross and fired past keeper Marco Silvestri from six yards.
Bellusci then spectacularly headed past his own keeper to double the hosts' lead and give Boro a comfortable half-time advantage.
Alex Mowatt saw a free-kick tipped over the bar early in the second half by home keeper Dimi Konstantopoulos and Antenucci's shot was ruled out as Leeds, who were without injured top scorer Chris Wood, sought a way back into the game.
But Boro sealed all three points when Fabbrini capitalised on a Sol Bamba slip to round Silvestri and fire home from a tight angle.
Middlesbrough manager Aitor Karanka:
"I don't think the goal incident is something that would have changed the game. I don't think the referee was important for the outcome of the game.
"I don't think the score is a reflection of the game. But the main thing is that we have won and we have another three points on the table.
"I knew this was going to be a very difficult game - and it was. We are only in September, though, and we have to keep going."
Leeds manager Uwe Rosler:
"The referee had a poor day. He [the linesman] told me he had to ask the referee so he wasn't sure. How can you give offside when you're not sure? He has to be 100% sure.
"It was the turning point in the game. You can't even be sure watching on TV.
"When you're overly nice you don't get far in life sometimes. I told them they should have gone over [to the linesman]. From now on, we will."
- 4AyalaBooked at 78mins
- 7LeadbitterSubstituted forForshawat 87'minutes
- 18StuaniBooked at 31minsSubstituted forFabbriniat 56'minutesBooked at 73mins
- 27AdomahSubstituted forNsueat 77'minutes
- 10De Pena
- 23L Cook
- 20BotakaSubstituted forDoukaraat 64'minutes
- 15DallasSubstituted forMurphyat 79'minutes
- Neil Swarbrick
- Shots on Target
Second Half ends, Middlesbrough 3, Leeds United 0.
Corner, Middlesbrough. Conceded by Sol Bamba.
Foul by Charlie Taylor (Leeds United).
Diego Fabbrini (Middlesbrough) wins a free kick on the right wing.
Attempt blocked. Mirco Antenucci (Leeds United) left footed shot from outside the box is blocked. Assisted by Souleymane Doukara.
Foul by Lewis Cook (Leeds United).
Tomas Kalas (Middlesbrough) wins a free kick on the right wing.
Substitution, Middlesbrough. Adam Forshaw replaces Grant Leadbitter.
Foul by Mirco Antenucci (Leeds United).
Adam Clayton (Middlesbrough) wins a free kick in the defensive half.
Corner, Leeds United. Conceded by George Friend.
Attempt blocked. Mirco Antenucci (Leeds United) right footed shot from the right side of the box is blocked. Assisted by Souleymane Doukara.
Goal! Middlesbrough 3, Leeds United 0. Diego Fabbrini (Middlesbrough) right footed shot from the right side of the six yard box to the top right corner.
Substitution, Leeds United. Luke Murphy replaces Stuart Dallas.
Attempt blocked. Alex Mowatt (Leeds United) left footed shot from outside the box is blocked.
Daniel Ayala (Middlesbrough) is shown the yellow card for a bad foul.
Mirco Antenucci (Leeds United) wins a free kick in the attacking half.
Foul by Daniel Ayala (Middlesbrough).
Substitution, Middlesbrough. Emilio Nsue Lopez replaces Albert Adomah.