Team Sky's Geraint Thomas has withdrawn from the Great Britain team for the upcoming World Championships in Geelong.

The 24-year-old and Jeremy Hunt were unveiled last month as the two riders who would be supporting Mark Cavendish's bid for the rainbow jersey, but the Welshman confirmed on Thursday he will no longer participate as he is still feeling the effects of his recent Tour de France campaign.

Thomas said: "I'm not going to be riding because I haven't felt too good since the Tour.

"I had a bit of down time and then at Eneco Tour I was struggling to get back into it.

"I decided to just pull out of the Worlds because I don't think I'll be 100% there. I thought it would be better to step aside and let one of the other guys ride who are going to be more motivated and going a bit better."

British Cycling performance director Dave Brailsford has announced that David Millar, already in the time-trial squad, will take Thomas' place in the road team.

"Following selection, Geraint was feeling tired in subsequent races and felt the road worlds were out of reach," said Brailsford.

"David Millar has now been selected to ride the road race as well as the time-trial and based on his current form we believe he will work well with Jeremy to give Mark the best chance at the road worlds."

Cavendish's chances of success had been earlier hindered by the UCI's decision to allocate Britain just three of a maximum nine places in the event, and although Thomas admits the numerical disadvantage will make life difficult for Cavendish, he believes the Manxman could still prevail.

"It definitely limits Cav's chances, only having two guys to help him," added Thomas. "He's just got to try to hang in there.

"He can look after himself a bit and he's got that respect in the peloton - people want to be on his wheel, rather than trying to fight him for somebody else's wheel. That's a big advantage for him."