World champion Rui Costa slipped out of the top-ten today (Image credit: Tim de Waele/TDWSport.com)

World champion Rui Costa (Lampre Merida) has been forced out of the Tour de France following an outbreak of pneumonia. The Portuguese rider was 13th on the overall standings ahead of the Tour's 16th stage to Bagnères-de-Luchon.

Costa had been suffering from bronchitis ahead of the second rest day at the Tour which was being treated with antibiotics. On the morning of the rest day in Carcassonne, Costa awoke complaining of general weariness and worse then in previous days with Lampre's team doctor, Dr Beltemacchi, subjecting him to tests and an x-ray at a clinic in Pezenas which revealed the diagnosis that he would not be able to continue the race with his pneumonia developing into bronchopneumonia.

A final decision was made on the morning of stage 16 as Costa was keen to assess his conditions after a night of rest and respect of the race as world champion only for the persistent effects of the illness to force him to retire from the race. The team also announced that there was a risk of Costa having to end his season early if he continued on in the race.

Costa wrote on his personal Facebook page that if he continued "besides endangering my health, I jeopardize my own career, so I made ​​this decision: I will leave the Tour.

"I apologize to all of you friends, my team and the organization of the Tour de France, but my health does not allow me to continue," he added. A picture of Costa's x-ray accompanied his message.