Newport Gwent Dragons back Jack Dixon has been ruled out for up to six months after suffering a kidney injury.
The 20-year-old uncapped centre was injured during the Dragons' 20-29 friendly defeat by Scarlets on Friday.
Dixon was in Wales' initial World Cup training squad for conditioning camps in Switzerland, Qatar and north Wales.
He was released by Wales boss Warren Gatland alongside British and Irish Lions Richard Hibbard, James Hook and Mike Phillips.
"It's very sad," said Dragons director of rugby Lyn Jones. "He's made good progress in his short career and he's trained well with Wales in the summer, but unfortunately didn't make the cut.
"We were expecting big things from Jack but unfortunately his development has again been curtailed with a nasty injury to his kidney, which is going to keep him out for three to six months.
"We'll have to assess his recovery come November."
Dixon made 20 appearances for Dragons last season, scoring four tries.