West Ham centre-back Kurt Zouma is facing an extended spell on the sidelines after scans confirmed he suffered a hamstring tendon injury against Chelsea.
Zouma, who has been in excellent form this season, managed 71 minutes of the Hammers' 3-2 victory over his former before going down clutching his leg.
He was quickly sent for scans by the club's medical department and West Ham have now confirmed the full extent of Zouma's injury on their official website.
"West Ham United can confirm that Kurt Zouma sustained a hamstring tendon injury during Saturday’s Premier League victory against Chelsea," a statement read. "A scan on Monday revealed the damage and the 27-year-old French international defender has already started his recovery programme at Rush Green under the supervision of the medical team."
No recovery period has been given for Zouma's injury, but there are fears that he could miss a significant number of games - which is a real concern for David Moyes as he is already without fellow centre-back Angelo Ogbonna.
Ogbonna's season may well be over after suffering an ACL tear before the November international break, leaving Moyes with just Issa Diop and Craig Dawson as senior centre-back options.
Zouma's injury could see West Ham step up their interest in Manchester City's Nathan Ake, whom 90min revealed as a target for the Hammers earlier this month.
Ake was identified as the primary centre-back target for West Ham even before Zouma went down, with the Hammers keen to pursue a loan deal for the Dutchman that could include an obligation to buy permanently in the summer.
Moyes' scouting team have also been keeping an eye on Championship trio Rob Dickie, Dael Fry and Lloyd Kelly of QPR, Middlesbrough and Bournemouth respectively.