Phil Jones limped off with an injury during Manchester United's 2-1 defeat at Huddersfield to cause more selection problems for Jose Mourinho.
Jones looked to be holding his thigh as he was substituted on 23 minutes and replaced by Victor Lindelof.
The United manager is already without centre-backs Marcos Rojo and Eric Bailly, although Mourinho hopes the latter will be back in contention next week.
Jones, who has played in all eight of United's Premier League games so far this season, is reported to have told journalists in the tunnel at full-time that he had injured his quadriceps.
The 25-year-old's replacement Lindelof was culpable for the two goals United conceded in the first half and it means Mourinho has a dilemma at centre-back ahead of their EFL Cup clash at Swansea on Tuesday.
Mourinho was scathing of his side's performance at Huddersfield, admitting the hosts won "on attitude".
Manchester United visit Swansea in the Carabao Cup on Tuesday, live on Sky Sports Football from 7:30pm.