Wales hooker Matthew Rees could miss the whole of the Six Nations with a groin injury.
The 29-year-old Scarlets star sat out Saturday's 30-17 tournament opening loss to England at Twickenham and is set to be sidelined once again for this weekend's clash against Scotland in Cardiff.
Fellow British and Irish Lions front-row Gethin Jenkins, who also missed the England match, could be available for this coming Saturday's international at the Millennium Stadium following a calf muscle injury.
Rees, capped 34 times since he made his debut against the United States in 2005, may need surgery and Wales team physiotherapist Mark Davies said on Monday: "We need to allow it to settle down. It is about what is the best option for Matthew."
But he was more encouraged by Jenkins's progress, adding: "At this moment in time, it is looking good."
Despite provoking the ire of Wales coach Warren Gatland lock Alun Wyn Jones could escape being dropped for the Scotland clash.
The 24-year-old law student was sin-binned for tripping England prop Dylan Hartley and in his absence the hosts scored 17 points without reply.
However, he may be given a chance to redeem himself when Gatland names his side to play Scotland on Tuesday.
"We all make mistakes and he made one on the weekend. It was one of those things and we move on," Wales assistant coach Neil Jenkins said on Monday.
Asked if he thought Jones would be dropped, former Wales outside-half Jenkins replied: "I don't think so."
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