West Ham have been dealt an injury blow ahead of the Premier League double-header against Liverpool.
Jurgen Klopp's runaway league leaders will meet David Moyes' Irons twice over the next month, with December's postponed fixture due to Liverpool's involvement in the World Club Cup being played next Wednesday (29 January) before the return fixture at Anfield on Monday 24 February.
Attacking midfielder Felipe Anderson missed the Hammers' draw with Everton last weekend through injury and Moyes has now confirmed the Brazilian is likely to be missing for around a month.
Updating the press on his injured players ahead of West Ham's game at Leicester on Wednesday night, Moyes said: "Felipe's got a problem with his back, which looks like it's going to keep him out for about four weeks.
"Michail Antonio is getting closer to fitness but Yarmolenko is the best part of three weeks away. We could do with getting them back."
Anderson scored his first goal of the season when the Hammers beat Bournemouth 4-0 in Moyes' first game back in charge earlier this month.
He arrived at the London Stadium in the summer of 2018 for club record fee of £36m and scored nine league goals in his first season at the club.
