Bath have promised to do all they can to get Taulupe Faletau fit for club and country again as soon as possible.
The Wales and Lions star – who has been ruled out of the World Cup in Japan after being dealt another cruel injury blow – is not expected to play again for three to four months after suffering a collarbone injury in training.
It means he will miss the tournament in what is a huge blow to Wales as well as to a player desperate to overcome recent injury problems.
Instead of trying to help Wales win the tournament, Faletau will be back at Bath where he has got used to rehabilitation sessions following serious injuries.
Bath rugby director Stuart Hooper said: “Any time a player misses out on a major competition is hugely disappointing.
“We are all feeling the impact of this news, especially as it follows a number of unfortunate and frustrating injuries for him.
“We will plan and support Toby’s (Taulupe’s) recovery, making sure it is the very best for him, in order to maximise his successful return to the game.”
The Welsh Rugby Union said the Bath No.8, who has won 72 caps and played in four Tests for the British and Irish Lions, will require surgery following what it described as “an innocuous training ground incident.”
In a statement, the WRU said: “Taulupe Faletau has been ruled out of Rugby World Cup contention due to a clavicle injury.
“The injury was sustained in an innocuous training ground incident and will require surgery.
“A prognosis and return to play time-frame will be established after surgery.
“The Wales squad and management would like to wish Taulupe the very best with his recovery.”
It is the latest major setback for Faletau, who broke his arm twice last season and has not played for Wales since March 2018.
But he has trained with Wales this summer and was recently part of an intensive two-week camp in the Swiss Alps as he built towards potential World Cup selection.
Only last month, Faletau spoke about his hunger to play again after being sidelined for so long.
The 28-year-old’s absence will be keenly felt, although Wales have considerable back-row resources.
The likes of Ross Moriarty, Josh Navidi, Aaron Shingler, Justin Tipuric and Aaron Wainwright are among those in head coach Warren Gatland’s training squad.
Gatland is due to name his final 31-man World Cup squad in early September, with Wales’ opening game being against Georgia in Toyota City on September 23.