Manchester United are sweating on the fitness of Luke Shaw after Erik ten Hag confirmed the star had "complaints" before he was subbed off against Aston Villa.
The Red Devils were leading 1-0 at half time thanks to Rasmus Hojlund's strike when the blow occurred.
But United, who secured a 2-1 win late on thanks to Scott McTominay, were forced into a reshuffle at the break when Shaw had to be taken off just two weeks after making his return from injury.
And Ten Hag revealed afterwards that Shaw had not been feeling right physically towards the end of the first period, resulting in him deciding not to take any further chances with him.
The Dutchman said as cited by Sports Central: “Precaution.. “He had some complaints and we can't take any risks with him because he's had any injuries in the past. We'll have to see how it goes in the next few days.. “It's not an advantage to lose him, everyone knows my philosophy to have left-footers at left centre-back and left-back. We have to make compromises and it is not to our advantage.”
Victor Lindelof, who is more accustomed to playing on the right, replaced the ex-Southampton man at left-back.
The 28-year-old Shaw firstly suffered an injury in the 2-0 defeat at Tottenham on August 19.
He then did not play for over three months due to what was described as a serious thigh muscle injury.
The defender did return to the first-team in late November but he suffered further misery two days before Christmas.
He then missed the rest of the festive period due to a muscular problem.
Shaw returned to action in the 4-2 FA Cup win at Newport County on January 28 and has started the victories over Wolves and West Ham since.
Another potential spell out for him further adds to Ten Hag’s injury woes.
Fellow full-back Aaron Wan-Bissaka missed the trip to Villa.
The 26-year-old has been plagued with injuries this term and picked up a problem before United's FA Cup win against Newport County.
Wan-Bissaka subsequently missed the Red Devils' wins over Wolves and West Ham in the league, but returned to training this week.
However, Ten Hag revealed the full-back had to pull out of training on Thursday.
He lost centre-half Lisandro Martinez during his side's 3-0 victory over West Ham last weekend.
Mason Mount and Tyrell Malacia are also out of action for United through injury..