The 28-year-old smartly struck home at the near post after shaping to cross just three minutes after being introduced, securing a 1-0 win at San Siro and 2-1 aggregate triumph.

“When you win a game of football away from home in a stadium like this against a team like this, you’re very happy,” 1999 treble hero Solskjaer said.

“We started really well I felt. First 15-20 minutes I thought we looked like a very good team.

“Then there was a spell from halfway through the first half to half-time that we rushed things, missed the ball, lost the ball too often, made it a long game.

“I just had to reiterate a couple of things and second half I felt we were much, much better.”

United left-back Luke Shaw felt they were “awful” in the first half but said “it always helps when you’ve got a world-class player like Paul to come on”.

The France international certainly added an extra dimension but Solskjaer believes he remains well short of his match-fit best.

“Paul looked like he’d been out for six weeks, yeah, for sure,” said the United boss, whose side take on Leicester in the FA Cup quarter-finals on Sunday.

“He’s been working really hard but when you play football it’s different and you can see that he needs… he couldn’t play more than 45 and he’ll get better and better.

“That’s a big, big boost for us rest of the season because the boys have done fantastic without him but we know Paul’s qualities.

“Marcus had a little twinge that we couldn’t take a risk with him but hopefully he won’t be too bad.”

Harry Maguire and Victor Lindelof were solid at the heart of the visitors’ defence, while Dean Henderson produced a key save from ex-United striker Zlatan Ibrahimovic a week on from allowing Simon Kjaer to level at the death.

“It’s a save he should have made last week! Very similar,” Solskjaer said. “No, very pleased for him of course. Great save. The team is always giving us everything you know.

“It started from the front with the pressing, the front four really high energy pressing and of course the back-six plus the keeper we know what they can do.

“Very happy with our defensive foundation. That gives you the platform to go and win games.”

While United can look forward to Friday’s quarter-final draw, Milan boss Stefano Pioli was left rueing what could have been.

“We are disappointed because over the two legs we played like a great team and we could have scored in the first half,” he said.

“I think the team deserved to continue (in this competition), but we had to give it a little bit more. I don’t think we deserved to go out.

“Over the two legs, we did so much right, but the two goals we conceded were more down to our own errors – that’s what is disappointing.”