Ole Gunnar Solskjaer took responsibility for Manchester United's disjointed performance against Reading in the FA Cup, admitting his changes to the line-up affected the team in their 2-0 win.

Juan Mata's penalty and a Romelu Lukaku strike in the first half were enough to send United into the fourth round, although the manner of their victory was unconvincing.

Reading, who sit 23rd in the Championship, had 59 per cent of the possession and 13 shots to United's eight, but failed to make the most of some promising openings in attack at Old Trafford.

Solskjaer accepted making nine changes to the team that started the 2-0 Premier League win over Newcastle United took its toll, but he reserved particular praise for Matteo Darmian - deployed as a makeshift centre-back - and debutant Tahith Chong.

"It was always going to be difficult with my team selection," he said. "I made it hard for the players, to be fair, because it's a team that's never played together. Matteo played out of position as well, but I thought he was excellent.

"Reading made it really difficult for us. We never had a kick the first five minutes. They just kept possession and we weren't cohesive enough in the pressing. That happens when you don't have a team that plays together as much, and we didn't have time to work too much on it."

On Chong, who came off the bench for Mata 62 minutes in, United's caretaker boss said: "He had two or three really good moments, as you do when you're young. You don't run the game as a first performance for a 19-year-old.

"But he got the crowd going and has shown one or two glimpses of what he can do. He has in training, anyway. And the game wasn't won, it was 2-0 and was still, 'go out there and perform'. It's not like it was 4-0 and it's just a party, so he did well defensively as well, and I think he'll remember this for a long, long time."

Mata's opening goal came after referee Stuart Attwell penalised Omar Richards for a foul on the Spaniard, which occurred just before Fred put the ball in the net but was flagged for offside, after a lengthy VAR consultation.

"From where I sat, it was a clear penalty," Solskjaer said. "I didn't need VAR, but they were probably checking if it was offside or not. Well done by Juan: he gets the ball down and the penalty was well struck."