Casey out for six weeks
Ireland lock forward Bob Casey, the London Irish captain, will be out for six weeks after an operation on his right bicep.
Club coach Toby Booth said: "We're hoping for a speedy recovery because he's our captain and the talisman of the team.
"He has had an operation and it's probably going to be six weeks or so".
It comes as a serious blow to the Guinness Premiership title ambitions of London Irish, who have also lost full-back Peter Hewatt for five weeks.