West Ham midfielder Manuel Lanzini faces up to six weeks on the sidelines after the recurrence of a thigh injury.
The 22-year-old, who has impressed on a season-long loan from Abu Dhabi club Al Jazira, was hurt in the 2-0 win over Liverpool on 2 January.
The Argentine will be out for "five to six weeks", club co-owner David Gold wrote on Twitter.
Lanzini sustained the initial injury in training last month and spent three weeks on the sidelines.
He returned earlier than expected as a substitute in the 2-1 win over Southampton on 28 December, but then went down after hitting the post with a swerving drive in the subsequent game against Liverpool.
Manager Slaven Bilic said after the game that it was a tendon problem.