England second row Simon Shaw could miss the entire RBS 6 Nations Championship after sustaining an ankle injury in Wasps' 19-3 Heineken Cup defeat by Munster yesterday.
Shaw was carried off on a stretcher in the 49th minute after falling awkwardly beneath a pile of bodies and sustained soft tissue damage.
A Wasps spokesperson said: "There was no break to the ankle but Simon sustained soft tissue damage. He is still in discomfort and will be out for several weeks."
Wasps director of rugby Ian McGeechan was unhappy with the performance of referee Nigel Owens and blasted his decision to give Shaw a yellow card for not retreating 10 yards at a penalty.
The Scot said: "Simon's sin-binning was crucial but these are the things that you have to live with in big games.
"We were on the receiving end of some tough calls and in a marginal game it's the little things like that become huge.
"Some of those decisions in the first half, had they gone for us, might have swung the pendulum in our way."
Ireland fly-half Ronan O'Gara booted 14 points with a flawless kicking display to lead Munster's assault while Denis Leamy broke Wasps' resistance with a late try.
The defending champions finished third in Pool Five following Clermont's triumph over Llanelli and McGeechan conceded Munster were worthy winners.
He said: "We're disappointed. We said who missed out in this group would be unlucky because it was such a tough group."