Belgian cyclist Frederiek Nolf, competing in the Tour of Qatar, was found dead in his bedroom Thursday morning prior to stage five, one of the race chiefs, Eddy Merckx, announced.
Nolf, a member of the Topsport Vlaanderen team, was found dead by teammate Kristof Goddaert in their 14th floor shared room at the Ritz-Carlton.
Organisers of the race, ASO (Amaury Sport Organisation) confirmed the death of Nolf and the day's stage — from the Camel Race Track to the Doha Foundation — was preceded by a minute's silence in his memory while the race was to be 'neutralised' out of respect for him.
"Out of respect for Frederiek Nolf, the riders will form a cortege throughout the stage," said Merckx.
Nolf's teammates, in shock at the news, did not start the stage.
The Belgian rider, who turned professional last year, would have celebrated his 22nd birthday on February 10.
Race director Christian Prudhomme said a ceremony in memory of Nolf would be held following the stage at six p.m. (1500 GMT) at the team hotel.
Goddaert said he found Nolf unconscious and tried, in vain, to wake him before alerting team officials and a team doctor.
"I tried shaking Frederiek's leg and told him to waken up, but I quickly realised that something was wrong. I took his hand but it was cold and there was no pulse," said team manager Jean-Pierre Heynderrickx.
The Belgian cycling legend added: "I spoke to his team manager (Heynderrickx) who told me there was nothing to indicate that something like this could happen. Yesterday (Wednesday) Frederiek seemed in good health."
Nolf's body was to be quickly repatriated to Belgium where his parents and fiancee had been informed of his death, the Belgian ambassador said.
An autopsy would follow to determine the causes of death.
The last time a professional cyclist died in his sleep was in 2003 when Frenchman Fabrice Salanson, 23, died in similar circumstances at the Tour of Germany.
Qatar race leader Tom Boonen said everyone on his Quick Step team was shocked.
"When something this awful happens, racing becomes a lesser priority. We're all devastated," said Boonen.
"We all knew Frederiek, and we all appreciated him. Today we wanted to remember him. Tomorrow the race will resume, but it won't be the same. The entire team, riders and personnel, feel his family's pain."