Ole Gunnar Solskjaer appeared to suggest Victor Lindelof could be facing surgery after aggravating a back injury during Manchester United's 2-2 draw with Leicester City on Saturday.
Lindelof has been nursing a back problem since November and was forced off in the 66th minute at the King Power Stadium, where he was deployed at right-back, on Boxing Day.
The Sweden international has only sat out one Premier League game for United this season but Solskjaer hinted he could now be facing a spell on the sidelines.
"He's struggling with his back. He struggled for a little while so we might have to do something. Let's see what it is," Solskjaer told BT Sport.
United took the lead through Marcus Rashford – who became the third-youngest player to reach 50 Premier League goals for the club after Wayne Rooney and Cristiano Ronaldo – but went into half-time level after an equaliser from Harvey Barnes.
Bruno Fernandes, who set up Rashford for the opener, put the Red Devils back in front in the 79th minute but Axel Tuanzebe deflected a shot from Jamie Vardy into his own net as the spoils were shared.
United midfielder Fernandes has now been involved in over half of the team's top-flight goals (31 of 60) since his debut on February 1, scoring 18 and assisting 13, while he is the first Portuguese player to score 10 or more goals in a Premier League season since Ronaldo did so in 2008-09.
"You can't think that before the game's over and the whistle is blown. Disappointed we don't win this afternoon because we had loads of good chances and we could have finished it off. But they're a very dangerous side and the goal from Vardy just shows his quality," said Solskjaer
"[Fernandes] always is [involved]. Good goal. Good pass by Edinson [Cavani], good timing, we'd just had a similar type of chance before - Anthony's chance.
"Both [Leicester] goals should've been closed down quicker. First one, definitely. Second one, down the side there we should manage to stop the cross. You always look at the goals conceded as you should've and could've done better.
"We've got a game in three days, we've got an extra recovery day that we'll use wisely. It's not the worst result but we're disappointed we didn't get away with three here because we were playing a good side."
United are unbeaten in their past 14 away Premier League games, their longest such run since a 16-match streak ended in January 2011, but could find themselves seven points behind leaders Liverpool on Sunday.