West Brom forward Nacer Chadli has been ruled out for up to two months with a reoccurrence of his hip injury.
The £18million record signing limped off in the 3-1 defeat at Stoke a week ago and he is unlikely to return before March.
Chadli has made just three league appearances this season because of his initial hip problem and his absence adds to Albion's problems.
They have scored just twice in six games under boss Alan Pardew, are second bottom of the Premier League and winless in 18 games ahead of Sunday's visit of Arsenal.
Pardew said: "Nacer looks like his injury is as bad as it was originally. We think he's going to miss the first two months of this year which is a big blow for us. Coming out of the Stoke game that was probably as big a blow as the defeat.
"It's something we're going to have to deal with and something I'm going to have to look at in January, because obviously he's a quality player going out of the group for some considerable time.
"On the medical side of that issue, they ticked all the boxes and more, we were just a little bit unfortunate it reoccurred and that can happen.
"Next time we'll have to be even more cagey and careful - that is probably why I'm saying two months rather than less, which it could be.
"Not only does he want to do well for the club, me and the fans, but he also has the World Cup around the corner.
"He's disappointed and upset but he'll be OK, and he'll get his head around it. He's experienced enough to do that."
Salomon Rondon (hamstring) is a doubt to face the Gunners and James Morrison (Achilles) remains out.
Meanwhile, Albion players and staff have donated money to the family of former mascot Richard Eades, who died suddenly on Boxing Day.
Eades had worked in various roles, starting with work experience, at The Hawthorns for 30 years and the club were keen to help the 42-year-old's fiancee and two young children.
" One or two were very conscious to do something more because there was that attachment," added Pardew.
"But everyone has pulled together and I think the club and players have done a great job. Their response has been great."