Cardiff - Wales flank Dan Lydiate broke his ankle playing for the Newport-Gwent Dragons on Friday and could miss the rest of the season, jeopardising his chances of making the British and Irish Lions tour of Australia next year.
The 24-year-old, who was named the Six Nations player of the tournament earlier this year as Wales swept to another grand slam, hobbled off after three minutes of the Dragons' 32-12 home win over Edinburgh in the Pro 12 league, which features sides from Wales, Scotland, Ireland and Italy.
"Sadly Dan has been taken to hospital after breaking and dislocating his ankle and will undergo surgery on Sunday morning," Dragons team manager Rob Beale told Welsh media after the win.
"It's a serious injury that requires surgery and he will be out for some time."
The Dragons did not say how long the tough tackling flank will be out of action for but the severity of the injury means he is highly unlikely to play in the November and December tests against New Zealand, Australia, Argentina and Samoa or the Six Nations, which starts in February.
Lydiate, who has 27 Welsh caps, was expected to earn one of the highly competitive back-row places for June's 10-match Lions tour, which features three tests against the Wallabies.
Wales coach Warren Gatland will take charge of the Lions and is expected to name his squad, boasting the best of talent from England, Scotland, Wales and Ireland, in April or May.
"It's a huge blow for him and for us. I don't know the time scale yet or how long he will be out. Let's just hope he still has a chance to achieve his goals," Dragons head coach Darren Edwards said.