Rangnick struggles to explain Rashford's loss of form after Man United advance in FA Cup

Striker has scored just three goals since returning from injury in October

Marcus Rashford shakes hands with iManchester United's interim manager Ralf Rangnick after being substituted during the FA Cup third round match against Aston Villa at Old Trafford. Reuters

Manchester United's interim manager Ralf Rangnick was at a loss to explain Marcus Rashford's ongoing struggles for form after another ineffective performance in the FA Cup win over Aston Villa on Monday night.

United progressed to the fourth round following a 1-0 win at Old Trafford, courtesy of Scott McTominay's eighth-minute goal, although it was another unconvincing display by the hosts.

Among the United players to struggle was Rashford, whose second-half substitution was met by sarcastic cheers from some supporters, while other fans countered by serenading the England forward.

Rashford, 24, has only scored three goals since returning from a shoulder injury in October and managed just 10 goals in the last calendar year. He had been dropped for the Premier League matches against Burnley and Wolves, but returned to the side to face Villa after impressing on the training ground.

"Actually I don't know," said Rangnick when asked if he could explain Rashford's dip in form. "I think he's trying hard. In training he was doing well in the last couple of days, that's why he was quite rightly in the starting XI.

"I think in the first half we found him quite often, but we also tried to get him into the box. In the second half that was not that often the case and that's why at the end of the game I decided to make two changes with Anthony Elanga and Jesse Lingard.

"It was very important to progress into the next round. Yes [confidence is important] especially for strikers - it's important that they score goals on and off, that there are moments of success.

"Of course it would be good, for example, for Marcus if he could score a goal but as long as he's trying, as long as he's training well I don't see that much of a problem."

While United were not entirely convincing, Rangnick said there were many positives to take away from the game as the same two sides prepare for an immediate rematch in the Premier League on Saturday.

Man United v Aston Villa player ratings

"We knew from the beginning that it will be a challenging game for us against a very flexible Villa side with their rotations that they're doing during the game all the time between their full-backs and their [number] eights," the German said.

"I think we saw quite a few pros today. I think we were better, we had a better structure. We also had good energy in the team, we moved the ball, in the first half especially, good within our team, with quite a few good diagonal balls.

"That was exactly what we intended to do against their rather central team and that was exactly the way how we created our first goal.

"But we're still struggling in the centre of the pitch. That's why Villa also had their moments where they could have scored."