Wales number eight Taulupe Faletau has undergone surgery on his broken arm to rule him out of the remainder of the Guinness Six Nations.
The 28-year-old suffered the injury against Wasps in the Champions Cup last month and it was hoped Faletau would return for the final two rounds against Scotland and Ireland. However Warren Gatland must complete the tournament without the Bath number eight.
"We're gutted for Taulupe, but this is the best course of action for him moving forward as a player," Bath director of rugby Todd Blackadder said.
"We will know more in terms of time frames following the surgery, but we're looking forward to welcoming him back into the squad."
Faletau was due to be in Gatland's original 40-man squad for the Six Nations before a second broken arm of the season ruled him out.
The Wasps match was Faletau's first appearance following a 13-week absence after his first arm fracture, which also ruled him out of Wales' four autumn Tests.