Speaking before the results of the injury were confirmed, assistant manager Neil McDonald admitted that the midfielder has been suffering from a long-standing problem in that area, meaning the latest setback will have to be treated very delicately.
"He's had problems in the past with it, all season really," Sam Allardyce's No.2 told reporters, "and he got a real good kick on it.
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With just one win in their last seven league games, the Hammers are now just six points clear of the drop-zone but McDonald insists that the team are not looking anxiously over their shoulders.
"We've always looked up the table this season and we've always tried to get into the top 10 and, with a good result on Saturday, we can push ourselves a little bit closer to that," he observed.
"I think the away form hasn't been as good as we'd have liked. Our home form has been really, really good, even though we've lost a couple.
"We have to address that; we've got to be a little tighter and a bit more physical away from home and make sure we try and keep a clean sheet. If we can do that, that gives us a good chance to get back to winning ways on our travels."