Rangnick unsure why Rashford is struggling at Man Utd

The England forward, who has scored just three goals this season, failed to make an impact in Monday's third-round tie at Old Trafford and cut a dispirited figure when he was substituted in the final few minutes.

Scott McTominay's early header was enough to send United through to the fourth round, where they will play Championship side Middlesbrough, but they rode their luck against Steven Gerrard's impressive team, who had two goals ruled out by the officials.

Asked why Rashford was underperforming, interim manager Rangnick said: "Actually I don't know.

"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."

Rangnick admitted confidence was important for forwards but said he was not too concered by 24-year-old Rashford's goal drought.

"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."

Rangnick took some positives from the game as United returned to winning ways following last week's 1-0 home loss to Wolves in the Premier League.

"I think we saw quite a few pros today," he said. "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."

The teams will meet again in the Premier League on Saturday, this time at Villa Park.