Manchester United will monitor Ander Herrera's fitness ahead of the Manchester derby this week, sources have told ESPN FC.
Herrera played 90 minutes as United beat Burnley 2-0 at Turf Moor on Sunday, but he was left hobbling by the end of the game after taking a heavy knock on his ankle.
The midfielder is set to be assessed on Monday, although United are hopeful he will be able to shake off the problem in time to face Manchester City at the Etihad Stadium on Thursday.
Manager Jose Mourinho is facing an injury crisis ahead of a game that could see United leapfrog Pep Guardiola's team in the race for a top-four finish.
He will be without Zlatan Ibrahimovic and Marcos Rojo, who both suffered knee ligament damage against Anderlecht last week.
Juan Mata is another long-term absentee with a groin problem, while Chris Smalling and Phil Jones are doubts after missing the last seven games with knee and toe problems, respectively.
However, Mourinho has encouraged the pair to play to ease the burden on Eric Bailly and Daley Blind, his only two fit senior centre-backs.
"If I was Smalling or Jones, I would play Thursday, with anything, I would," Mourinho said after the game. "I wouldn't accept one guy to play nine matches in a row because I am injured. I would do a last push.
"If they have a crazy mentality like I have, they would [play on Thursday]. If they are safe thinking and they are surrounded by people with the same mentality they have, it is more time, more cautious. If it was me, nobody would stop me to play."
United are also sweating on the fitness of Paul Pogba.
The midfielder was forced off in the final minute at Turf Moor and Mourinho said afterwards he is unsure whether the midfielder will be ready to face City.
"I don't know," he said. "Dead he is for sure. If he's injured or if it's just the super accumulation of fatigue in the muscles, I don't know.
"But as I was saying, if he cannot play Thursday he cannot play Thursday. We play another one and we don't cry, like we didn't today."
Victory for United at the Etihad Stadium would lift them two points above City with five games remaining.
A fourth Premier League win in a row would also see United join third-placed Liverpool on 66 points.
Jurgen Klopp's side, who lost to Crystal Palace at Anfield on Sunday, do not play again until Monday when they visit Watford.