Mark Cavendish missed training on the eve of the Tour of Qatar after falling ill on yesterday's seven-hour flight from London to Doha.
"The team doctor assessed him last night and again this morning... everyone felt it was in his best interests not to ride with the others," Team Sky race coach Rod Ellingworth said.
"13hrs of sweat-drenched sleep hasn't shifted a fever that started on the plane over here. Really not feeling well today. Can't leave my bed," Cavendish posted on Twitter this afternoon.
Ellingworth added that Sky are "confident" that Cavendish will start the race - his first for the team - tomorrow, but that a decision on his participation will be made at 1000 AST (0700 GMT).
The Tour of Qatar gets underway with a 142.5km stage between Barzan Towers
and Doha Golf Club.
The Manxman has enjoyed success in Qatar before, winning two stages in 2009.
Cavendish recently indicated his desire to win all through the season. His first big goal of the year is Milan-San Remo.
Related linksTour of Qatar 2012: preview and coverage
Cavendish aims for winning season
Cavendish wins Worlds road race
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