A leg injury has added a new complication to Matthew Glaetzer's tumultuous Tokyo Olympics campaign.
The 2018 world sprint champion is out of the Australian team for the world track cycling championships after he suffered the injury last week in training.
It comes four months after Glaetzer revealed he had undergone surgery for thyroid cancer.
He returned to competition in December and then had more treatment.
Also on Thursday, Cycling Australia announced world champion team pursuiter Kelland O'Brien was a late withdrawal from the worlds team.
O'Brien needed surgery on a broken collarbone after he crashed out of January's Tour Down Under.
Thomas Cornish will take Glaetzer's place and Luke Plapp will come into the Australian team for O'Brien, with the two riders making their senior world championships debuts.
The Australian team left Adelaide on Wednesday for the February 26-March 1 worlds in Berlin.
It is a key pre-Olympics event for the track cyclists.
Glaetzer would have ridden in the sprint, keirin and team sprint events at the world championships.
His absence will further complicate Australian selection concerns around the men's team sprint for the Tokyo Olympics.
It is unclear for now whether Australia will enter the event for the Olympics, given the lack of success.
Cornish will compete in the team sprint at the worlds along with Rio Olympian Nathan Hart and Matthew Richardson.
Australian Associated Press
