Australian Michael Matthews will miss this year's Tour de France with a lung problem, his Jayco-AlUla team announced on Friday.
His team discovered a blood clot in his lung at a recent altitude training camp.
Matthews won the last of his four Tour stages in 2022, with this year's edition starting on 5 July.
"Matthews' health condition is stable," Jayco-AlUla said.
"The medical team are now thoroughly investigating the extent of the issue and possible cause, to define a safe and optimal recovery process for the athlete.
"During this period of investigation, as a safeguarding measure, Matthews will refrain from competition to ensure there is no risk to his health and well-being, therefore ruling out his participation in the upcoming Tour de France."