West Ham have announced that the thigh injury suffered by Manuel Lanzini will keep the on-loan midfielder out of action for up to six weeks.
The 22-year-old, who is on a season-long loan from Al-Jazira, hurt his quadriceps during training prior to the goalless draw at Manchester United on Saturday.
Hammers co-chairman David Gold said on Monday he was hopeful that Lanzini would be fit to face Stoke this weekend, but subsequent scans have put paid to that notion.
The Argentine is only expected to be available for selection again towards the end of January, having impressed his manager, Slaven Bilic this season, scoring four goals and providing one assist in his 12 Premier League appearances.
A statement on the club's official website read: "Lanzini underwent a scan on Monday and will now begin a period of rehabilitation which is expected to keep him out of first-team action for a period of up to six weeks."