Anthony Martial was left out of the Manchester United squad for Thursday’s Europa League win over Club Brugge after picking up a muscle injury in training.
United manager Ole Gunnar Solskjaer confirmed the French forward suffered the injury to his thigh on Wednesday.Solskjaer will be hoping he recovers in time for Sunday's Premier League clash at Everton, live on Sky Sports.
Asked how long Martial would be out for, Solskjaer said: "I don't know. He went off in training on Wednesday. He had treatment.
"He tried [to play] today to be fair. He reported and had a fitness test this morning but he was not [able to play].
"It is not his hamstring. It is his thigh, in and around the knee so I don't know."
Odion Ighalo was handed his first Manchester United start in Martial's absence and took full advantage, scoring his first goal for the club in the 5-0 win.
The deadline-day loan signing from Shanghai Shenhua was among seven changes to the side that drew in the round-of-32 first leg in Belgium last week.
Scott McTominay returned to the starting line-up for the first time since sustaining a knee injury on Boxing Day and he also got on the scoresheet.
Martial's injury is a blow for United. The 24-year-old had been in fine form, scoring in each of United's past three matches.
United are already without Marcus Rashford, who is out with a double stress fracture in his back. Solskjaer said last week the England international is "touch and go" to return for United this season.
The game against Club Brugge is the first of four in 10 days for United. They travel to Goodison Park on Sunday to play Everton in the Premier League, live on Sky Sports.
They then travel to Pride Park Stadium next Thursday to play Derby in the FA Cup fifth round, before hosting Manchester City in the Premier League on March 8, live on Sky Sports.