MANCHESTER, England -- Manchester United midfielder Scott McTominay suffered knee ligament damage during the win over Newcastle, according to Ole Gunnar Solskjaer.

McTominay left Old Trafford on crutches after being substituted at half-time during the 4-1 victory over Steve Bruce's side.

The 23-year-old was involved in a challenge with Sean Longstaff in the opening stages but was able to play on until the break before being replaced with Paul Pogba.

"He's done his ligament in the knee," said Solskjaer.

"I don't know how bad. Let's see. The boy has got the biggest heart, you see the attitude of the kid [to play on]. I'm not sure if he's going to be ready for Saturday [against Burnley] but we've seen him heal quickly before."

United moved to within four points of the top four with victory over Newcastle, which was secured thanks to goals from Mason Greenwood, Marcus Rashford and a brace from Anthony Martial.

Greenwood's goal -- his eighth of the season -- was a spectacular effort from outside the box that went in off the underside the of crossbar and Solskjaer has warned the rest of the Premier League that the 18-year-old is only going to get better.

"He's learning, growing as a human being," said the United boss.

"He'll grow more and more and we're not going to see the best of Mason for a couple for years. When I was 18 ... I was nowhere near the level he is now."