Cardiff Blues will be without Rhys Patchell for several months after the fly-half damaged his knee in their
21-13 win over Newport Gwent Dragons.
While the 20-year-old Wales international is sidelined, he will also have a shoulder operation to rectify a long-standing problem.
Patchell's absence is an untimely blow ahead of Blues' Heineken Cup match with Toulon in Nice on Saturday.
The injury also ends his hopes of playing in the Six Nations.
Rhys Patchell factfile
Born: 17 May 1993, in Llandough
Blues appearances: 37
Blues points: 208
Wales caps: Two
Patchell has won two caps for his country, both on the
Wales' tour to Japan
in June 2013, and was tipped to be included in coach Warren Gatland's squad for the Six Nations.
Wales begin their campaign with a home game against Italy on 1 February, with their last game in the competition against Scotland in Cardiff on 15 March.
Blues, meanwhile, are likely to give the number 10 shirt to Gareth Davies in Patchell's absence.
They are ninth in the Pro12 but second in their Heineken Cup pool, two points adrift of Toulon.
Director of rugby Phil Davies said: "It is a disappointment to us to lose Patch for this period of time when he is playing so well, with many crucial games coming up in both Europe and the Pro12.
"However, it will give others within our squad the opportunity to step up as we look to enjoy a strong start to 2014.
"We wish Rhys all the best with his rehabilitation, will give him the very best support and I know he will be determined to get back fit as soon as possible. We all look forward to seeing him back in a Cardiff Blues jersey in the coming months."