Stephen Roche, one of only two Triple Crown winners in cycling history, believes Team Sky's Bradley Wiggins is the overwhelming favourite to become the first Briton to win the Tour de France.

Roche won the Giro d'Italia, Tour de France and world championships in 1987 and the Irish rider is adamant Wiggins, who has a best finish of fourth on the tour, is a major contender for this year's title.

Defending champion Cadel Evans and Vincenzo Nibal will provide the biggest threat to Wiggins, who comes into the event in supreme form having finished on the podium in every race in the past 12 months.

Bradley Wiggins
Wiggins is favorite for the yellow jersey.

"Bradley Wiggins has to be the outstanding favourite for this year's Tour," said Roche.

"Let's not, though, neglect Cadel Evans who himself was a surprise winner last year.

"[Vincenzo] Nibali and [Frank] Schleck will be there or thereabouts but I can't see anybody rivalling Wiggins when it comes to the time-trials and I can't seen any of them putting enough time into him in the mountains.

"Schleck will lose at least six or seven minutes in the time-trials to Wiggins, so unless Bradley crashes or has a real loss of form he stands a real chance."

Wiggins' hopes, which has been assisted by consecutive wins at the Paris-Nice, the Tour of Romandy and the Criterium du Dauphine, have also been boosted by the absence of Andy Schleck and Alberto Contador.

Without the specialist climbers, the onus will be on the likes of Wiggins to lead from the front in the hill stages, while his dominance in the time trial, an event he won Olympic gold in on the track in 2008, stands him in good stead also.

"Of course, nothing is won yet," Riche warned. "There are another 197 riders in the race and we have previously seen how [Thomas] Voeckler rides and then there are many others who can cause surprises such as Sylvain Chavanel.

"Riders who once targeted a top 20 finish can now look at the top 10. When riders like Andy Schleck or Alberto Contador are in the race they climb at, say, two kilometres an hour quicker than most and that doesn't suit a lot of riders. So with those guys out of the race it is going to be a lot more open and I'm sure a lot are out there rubbing their hands saying 'well, I'm going to have a go here'. Again, guys like Voeckler and Chavanel will be thinking that.

"I wouldn't say it is the most open race ever because Bradley has shown himself over the last few months - at Paris-Nice, the [Tour of] Romandy and [Critérium du] Dauphiné - and proved he has improved in every area. One area that I think he has improved the most is in his tactics. He has grown in confidence and so his tactics have got better.

"Wiggins has become more of a leader who is willing to stamp his authority on a race. We saw him at the Dauphiné when he got his team to chase down a group and when they got to within 20 seconds he just clipped off himself. That was a great show of form."