Romelu Lukaku scored his 12th goal of the season as Chelsea beat Championship side Middlesbrough to reach the FA Cup semi-finals.

Middlesbrough had knocked out Manchester United and Tottenham on their way to the quarter-finals but their hopes of claiming another Premier League victim were dealt an early blow when Lukaku tapped in from Mason Mount's cross after a quick Chelsea counter.

Hakim Ziyech made it 2-0 midway through the first half with a superb dipping effort from the edge of the box before Lukaku was denied a second when Anfernee Dijksteel cleared off the line.

Middlesbrough showed plenty of endeavour in the second half as they looked to mount an unlikely comeback, with Arsenal loanee Folarin Balogun shooting wide after a promising counter, while Duncan Watmore also sent an effort over the bar from a good position.

However, Chelsea could have grabbed a late third when substitute Timo Werner met a free-kick but Middlesbrough goalkeeper Joe Lumley did well to palm away.

"I'm super happy because we were very focused," Chelsea manager Thomas Tuchel said. "There was a lot of effort against the ball and we did not allow big chances.

"We defended and attacked as a team. On the ball, we were calm and controlled the match. We managed to find ways through the gaps to escape their high pressing and find spaces behind the line and create fast attacks.

"We scored in decisive moments and in the second half we created more chances. I'm very happy and very impressed because it was another very focused performance and a deserved win."