Two-time world champion Becky James will not compete in the Commonwealth Games because of a knee injury.
The 22-year-old Abergavenny cyclist was one of Wales' main medal hopes for the track events in Glasgow this summer.
"Unfortunately I will be withdrawing from the Team Wales Cycling squad for the Commonwealth Games," said James.
James aggravated the knee injury when she returned to training following a period of rest after a minor medical procedure.
She won two gold medals at the UCI World Championships in 2013, and claimed a silver and a bronze for Wales at the 2010 Commonwealth Games in Delhi.
In a statement issued jointly by British cycling and Welsh cycling, James explained the injury followed a period of enforced medical rest.
"In May, I received abnormal results from a routine smear test and, following the biopsy results, I underwent minor surgery which I'm pleased to say was successful," she said.
"The surgery, however, meant [taking] two weeks away from my usual training regime.
"Following the rest, in an effort to make up for lost time, I aggravated a knee injury that will rule me out of the Games.
"I'm terribly disappointed I won't be competing in Glasgow. I still hope to be there cheering the team on, and I wish the entire team the best of luck."
Matt Cosgrove, performance director at Welsh Cycling said: "Although it is disappointing that Becky will be absent from the Team Wales cycling squad in Glasgow this summer, it is important that Becky now looks after herself and she is on the road to recovery.
"We look forward to seeing her back on the bike and competing in the near future."