Manchester United manager Erik ten Hag has confirmed that Mason Mount came off at half-time against Brighton & Hove Albion today because he had an issue.
The 25-year-old was replaced by Joshua Zirkzee, and the Man United boss is hoping he has not picked up a serious knock after he missed a large chunk of last term due to injuries.
Mount started against Fulham in the Premier League opener last weekend and produced an impressive performance against Brighton before he was taken off.
Man United struggled to continue to exert the same dominance they enjoyed in the first half after the break, and Brighton punished them with a last-gasp winner.
The Red Devils return to action next Sunday when they host Liverpool at Old Trafford, and they need Mount back for that game to boost their chances of winning.
The Englishman only played 14 league games in his debut campaign at Man United last term, starting five times.
Mount featured in six games across other competitions and will be desperate to prove himself this season, with a recall to the England national team also on his mind.
The knock he picked up today appears to be a little one, and tests will be carried out in the coming days to determine the nature of the issue.
Losing another key player to injury is the last thing the Red Devils need right now, having already lost Luke Shaw, Leny Yoro and Tyrell Malacia to injury.
The defeat gave Man United a timely reality check, reminding them they are not good enough to challenge for the Premier League title.
They need to make more quality additions to their squad before the transfer window closes on Friday.
