Manchester United reportedly fear that midfielder Paul Pogba could be ruled out for up to two weeks with a thigh injury.
The Frenchman has been absent from Ole Gunnar Solskjaer's side since he limped off in the 3-3 draw at home to Everton on February 6.
The Daily Mail reports that the 27-year-old could be out for at least a fortnight, which would see him miss both Europa League ties against Real Sociedad and the Premier League clash against Newcastle United on Sunday.
Pogba could be able to feature for either of the two vital top-flight matches against Chelsea on February 28 or the Manchester derby a week later, however there is no definitive timescale put on his return.
The midfielder's eventual return to action will come as a timely boost to United, who have seen their title hopes falter in recent weeks.
Pogba, who enters the final year of his United contract in the summer, has scored four goals and provided three assists in 28 appearances in all competitions so far this campaign.