West Ham United's Ukraine winger Andriy Yarmolenko is expected to be sidelined for about six months after an operation to repair a damaged Achilles tendon, the club said on Monday.
Yarmolenko suffered the injury in Saturday's 1-0 Premier League defeat against local rivals Tottenham Hotspur at the London Stadium and had surgery on Monday.
"Andriy's operation went well and we will now work hard to support him throughout the rehabilitation process," West Ham's Head of Medical Services Richard Collinge said in a statement.
"His recovery will be planned very carefully and we have every confidence that he will return to full fitness within the scheduled time frame."
Manuel Pellegrini's West Ham side are struggling in 14th place in the standings with seven points from nine games.