Belgian sprinter Tom Boonen, who was only given the green light to ride in Saturday’s opening stage of the Tour de France the day before, has been beset by diarrhoea and abdominal pains.

The 2009 Tour begins with a 15.5km time-trial around the Principality, but Boonen is suffering with illness brought on by the stress of only being told he can race on Friday after a Court of Arbitration for Sport (CAS) ruling.

Quick Step’s former world road race champion had been barred from the Tour by organisers following a positive test for cocaine in April, but was cleared to race in a ruling given by the CAS on Friday.

It was his second such test in a year. Boonen also missed the Tour in 2008 because he tested positive for the drug in May last year.

But the stress of waiting to hear if he can ride has clearly taken its toll on the 28-year-old.

“Tom does not feel very well: he has abdominal pains and diarrhoea,” said Quick Step team manager Patrick Lefevere.

“I think that it is a reaction from his body to what has happened over the last few weeks.”We will see how he is on a day to day basis.

“Tom is a strapping lad and, in the team we have other boys like Sylvain Chavanel and Stijn Devolder who are able to race more aggressively.

“Boonen’s big aims at the Tour de France will be winning some flat stages and challenging for the points classification’s green jersey.