Paul Merson says Michael Carrick needs Bruno Fernandes in his side and has challenged Matheus Cunha to find greater consistency after Manchester United's dramatic 3-2 comeback win over Roma.

United showed plenty of character to recover from two goals down in the Champions League on Tuesday, earning their first win in 10 games, but Merson believes the result should not disguise the problems that remain under Carrick.

Merson also questioned whether United can carry that momentum into Sunday's Premier League clash with Aston Villa, live on Sky Sports.

'You need Bruno on your side'

"I think Bruno Fernandes has to play for Manchester United. He's their best player, and when you're going through a difficult period, you need your best players on the pitch.

"It takes a lot to miss a penalty, then have the courage to step up and take it again. The pressure was severely on him, so fair play to him.

"I know he was left out against Roma, but I don't think you can keep leaving him out. Even if he's not playing particularly well, he still gets into Manchester United's team. They haven't got a player better than him.

"You couldn't keep chopping your nose off to spite your face. You need him on side.

"Brian Clough always used to say that when times are hard, go back to putting your best team on the pitch. Put it in your drawer, and when things aren't going well, go back to that team.

"That's what United need to do. Bruno has to be in it. As long as he plays well, they will always have a chance of winning.

"But I still think they need to become much more of a 90-minute team. They were very good against Chelsea in the first half on Saturday, and they had good spells in the second half against Roma, but you aren't going to win too many football matches playing like that.

"You need 70 or 75 minutes of good football, not 10 minutes here and 15 minutes there."

Cunha can't be a nine one week and a four the next

"Matheus Cunha is a passionate player, and I like that about him, but I said something in my column the other day about his performances. He's a nine or a four.

"At Wolves, he could be a nine one week and they would win a football match. The following week he might be a four and they wouldn't win. That's the nature of being at a club fighting towards the bottom of the table.

"But this is Manchester United. When you play for a club of that size, you've got to be a seven or a seven-and-a-half every week. You can be an eight, you can have a nine, but you can't be a nine one week and a four the next.

"That's the difference when you go to a big football club. These teams need to win week in, week out. They can't afford to rely on one outstanding performance every few weeks.

"Cunha might not have been used to those expectations at Wolves, but that's what comes with playing for Manchester United.

"Look at Carlos Baleba. He's only just arrived, and it was a shame to see him pull his hamstring. But he'll be sitting there thinking, 'when I was at Brighton and we lost, nobody said a word. Now I'm at Manchester United, losing against one of the top teams, and we're getting destroyed after the game'.

"That's the environment you're playing in. You're at one of the biggest football clubs in the world, and the standards have to reflect that."

Roma comeback showed bottle - but United rode their luck

"You've got to live in the moment, and it was an amazing comeback from Manchester United.

"At 2-0 down, given the run they've been on, it would have been difficult to get those players back out on the pitch for the second half. So I give them a lot of credit for that.

"They showed a lot of bottle but they rode their luck.

"Bruno gets the opportunity to retake his penalty. If they don't get that decision, do they get back into the game? Roma then make a mistake at the back, miskicking the ball. You shouldn't be doing that at this level.

"And for the winning goal, I don't really see a goalkeeper in the Premier League letting that one in at the near post.

"So, yes, credit where credit is due. It was a brilliant comeback and it could be the result that turns their season around. But I don't think you can look at that performance and say everything has suddenly changed.

"I feel sorry for Michael Carrick. I don't think it's him; I think it's the players."

Villa will provide a reality check on Sunday

"I don't see the Roma result as a turnaround for Manchester United. I think it's a start, but if I'm being honest, I don't see them getting anything from Aston Villa on Sunday.

"Villa weren't great against Barcelona, but they're playing a much better standard of football at the moment.

"Roma covered over the cracks, in my opinion. It's not like they absolutely destroyed Roma. They got back into it by bad luck.

"I'm more interested in what happens this weekend from Manchester United."