Wales forward Taulupe Faletau will miss the 2018 Six Nations due to a knee injury.
The Bath back rower suffered a grade three medial knee ligament injury in the European Champions Cup match against Toulon on Saturday and is likely to be out for up to four months.
"We're really disappointed for Taulupe - he's been in great form this season, so it's really unfortunate news," Bath's director of rugby Todd Blackadder said in a statement.
"However, he's in great hands with the medical team and we look forward to having him back on the pitch soon."
A repeat of the knee ligament injuries Faletau battled last season comes as an added blow to Wales after fellow back rower Sam Warburton was ruled out of the Six Nations, also due to a knee issue.
Warren Gatland's team begin their Six Nations campaign at home to Scotland on February 3.