Ralf Rangnick has confirmed Aaron Wan-Bissaka is an injury doubt for Saturday's Premier League game against Norwich at Carrow Road.
The right-back was stretchered off after colliding with an advertising board during Manchester United's game against Young Boys.
The incident happened in the final few moments of the Champions League fixture at Old Trafford on Wednesday.
Wan-Bissaka also suffered a knock to his wrist earlier in the evening after landing awkwardly.
Speaking after the game, Rangnick revealed the defender's injuries will need to be assessed over the coming days to see if he can play on Saturday.
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"It was also good to see Luke Shaw back," said the German. "Hopefully he can at least be a candidate for the Norwich game in the squad.
"Aaron got two knocks again. One on the wrist another one on the knee, so we have to see how this will develop by Saturday."
Wan-Bissaka will be hoping to return to action as soon as possible with fellow right-back Diogo Dalot impressing in the role of late.
The Portuguese has barely featured for United since joining the club from Porto in the summer of 2018 but did well against Crystal Palace last weekend.
He is likely to retain his place for the Norwich game and will have a chance to make it his own if Wan-Bissaka faces a spell in the treatment room.
Dalot was recently linked with a move to Jose Mourinho's Roma but told United's website he was determined to be a success at Old Trafford.
"It's not easy when you're outside and you don't play as much," he said. "But our job to keep ready and I think I was doing a fantastic job outside the pitch being ready.
''When the opportunity comes, I now feel I need to keep going and give everything when I'm on the pitch too.''
Speaking last month, Dalot insisted he enjoys the competition for the right-back spot at United and believes it's good for the team.
"The most beautiful and healthy competition is when there are two or three for each position and you can learn from each other," he said.
"I'm sure Aaron learns some things from me when I play, I learn from him. Everyone is going to be a part of it this season."
Wan-Bissaka was criticised earlier this season after United's humiliating defeats to Liverpool, Manchester City and Watford.
"You look at modern-day full-backs and you probably would expect a bit more from Wan-Bissaka," said Red Devils icon Gary Pallister earlier this month.
"Wan Bissaka is good at defending one-on-one, not many people get past him. As a centre-half, you do want your defenders to defend, but the best ones can do it both ways.
"I think that's something Wan-Bissaka needs to improve on. I don't think it's just me saying that, I think everyone who looks at it wants more from him."