West Brom are awaiting further news on the fitness of James Morrison, who has been forced to withdraw from the Scotland squad.
The midfielder was forced to leave the action in the second half of Saturday's defeat to Chelsea after a strong challenge from the Blues defender Jose Bosingwa.
Boss Tony Mowbray has revealed that Morrison suffered a medial knee ligament injury and that means he will play no part in Scotland's high-profile friendly with Argentina this week.
West Brom's medical team will assess the full extent of the problem this week but the midfielder looks a doubt for this weekend's big clash with Stoke at the Britannia Stadium.
Speaking to the club's website, Mowbray said: "He's tweaked his medial knee ligament, hopefully it's not too bad.
"These kind of injuries come in different grades and we are not to sure how bad it is."
The boss added: "The worst-case scenario is that he is out for four to six weeks. The best-case scenario is that it settles down after a couple days. Fingers crossed it's not too bad."