West Ham United defender Angelo Ogbonna damaged knee ligaments during Sunday's Premier League win against Liverpool.
Ogbonna, 33, was forced off with an eye injury during the first half but later complained of discomfort in his knee.
A scan on Monday showed the Italy centre-back, an ever present for the Hammers in the league this season, had damaged his anterior cruciate ligament.
He will see a specialist later this week to determine whether he needs an operation and a timescale of recovery.
West Ham rose to third in the table after Sunday's 3-2 victory against Liverpool at London Stadium.