West Ham midfielder Manuel Lanzini could be sidelined for six weeks with the thigh injury that kept him out of the weekend's Premier League draw with Manchester United.
Lanzini missed Saturday's goalless draw at Old Trafford, and West Ham confirmed the extent of the Argentinian's injury on Tuesday.
"West Ham United can confirm that Manuel Lanzini could be ruled out for up to six weeks with a quadriceps injury," read a club statement.
"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."
Lanzini has hit four goals and provided one assist in 12 Premier League appearances for West Ham so far this term, during his season-long loan spell from Al-Jazira in the United Arab Emirates.
The latest injury blow for Slaven Bilic's side follows the loss of Diafra Sakho for three months with a thigh problem of his own, while Victor Moses was still sweating on the results of a scan on his hamstring.