Is Mason Mount injured again? Erik ten Hag explains why he subbed midfielder at half-time in Man Utd's loss to Brighton

Mount started the contest at the Amex Stadium, keeping his place for the third successive game. But he didn't reappear for the second half and was replaced by Joshua Zirkzee.

Ten Hag hasn't suggested there is anything majorly wrong, but the reason it's still concerning for Manchester United fans is that Mount's debut season following last summer's £60 million ($76m) transfer from Chelsea was ravaged by injury. He managed just 20 appearances in total, five of which were Premier League starts.

"He had some problems and he had an issue. We know the history of Mason, so we took him out," Ten Hag told TNT Sports.

The United boss later told a press conference: "I don't know how much of a worry it is, I can't say at this moment. But I think we have a good bench and can bring in Zirkzee, then don't hesitate. Bring Mount off and bring [on] a player who can have an impact."

United staff and fans alike will hope that Mount has just a minor issue that won't rule him out for long. The next fixture is against Liverpool on September 1, followed by a break for September international matches.