Marko Arnautovic looks destined to miss a month of action with a muscle injury, according to West Ham boss Manuel Pellegrini.
The Austria forward limped off towards the end of the first half of the Hammers' 3-1 Premier League victory over Cardiff City on Tuesday, his replacement Lucas Perez scoring twice.
Arnautovic appeared to pull his hamstring and on Wednesday posted on Instagram to say he would be out for "a while".
Pellegrini was able to place a more definitive timeframe on his comeback, however, confirming the expected absence on Thursday ahead of West Ham's home clash with Crystal Palace at the weekend.
The Hammers are set for a favourable looking fixture list over the Christmas period, with games against Fulham, Watford, Southampton, Burnley and Brighton and Hove Albion to come after Saturday's London derby with the Eagles.