Tour de Suisse 2014: Sir Bradley Wiggins suffers another blow to Tour de France hopes after he is ruled out of Switzerland Tour with a knee injury

Wiggins is unlikely to feature in Team Sky's line-up to tackle the Tour de France

Wiggins on his winning ride in 2011 (Getty)

Doubts over Sir Bradley Wiggins’ participation in next month’s Tour de France have intensified after the injuries he sustained in a crash on Tuesday forced him out of a crucial warm-up race.

Wiggins did not start today’s stage of the Tour de Suisse as a result of a knee injury incurred the previous day when his bike became entangled with another rider’s and he fell.

When asked if this abandonment would affect Wiggins’ chances of racing the Tour, a Sky spokesman said, “He will be back on the bike in the next couple of days and the team will select the Tour line-up at some point after the Route du Sud and Tour de Suisse [stage races].”

However, Wiggins’ main target in the nine-day Tour de Suisse was tomorrow’s time trial. Evaluation of his current readiness to race the Tour de France by Sky may therefore be difficult to make. He was also ill earlier in the race with a chest infection.

The uncertainty surrounding Sky’s Tour selection first erupted two weeks ago, when Wiggins all but ruled himself out of the team for reasons that are still not totally clear. At that point, Wiggins’ race form was not an issue – in May he had won the Tour of California in convincing style – and he even claimed that he was at a similar level to his Tour-winning race condition of 2012.

Now, however, his form is an unknown, particularly after Tuesday’s bad crash, and the knock-on effect is an even greater muddying of the waters when it comes to his Tour participation. “I’ve got quite a lot of swelling on the left-hand side of my right knee,” he said.

“I probably could have started [today] but it’s best to play it safe... I really want to be ready for the [GB national time trial in Monmouthshire] next Thursday so I didn’t want to jeopardise that. The plan is to have 24 hours off the bike and then I’ll be good to go again and finalise my preparations for Wales next week.”

Sky’s injury list also includes 2013 Tour champion Chris Froome, who crashed heavily on Friday’s stage of the Critérium du Dauphiné – although there is no doubt he will be fit to defend his title. On the plus side, following a dismal start, Australian Richie Porte – expected to be Froome’s wing man in the Tour – showed fast-improving form in the second half of the Dauphiné.

In today’s stage of the Tour de Suisse, Mark Cavendish hit the tarmac in a spectacular late crash which wrecked his chances of fighting for a second bunch sprint win in a row.

As the pack jostled for position on a series of narrow, sharp bends, a rider went down ahead of Cavendish, and the Omega Pharma Quick Step leader fell, spinning over his handlebars. The Briton is not thought to have suffered major injuries, and he could remount and complete the course, but coming so close to the Tour, it was a narrow brush with disaster.