Tour de France 2013....

The final confirmation is lacking, but it looks increasingly certain that Bradley Wiggins will not defend his 2012 Tour de France title, but will race as a key wingman for Sky team-mate and this year's runner-up, Chris Froome.

Instead, Wiggins will concentrate on the Giro d'Italia, cycling's second biggest stage race. "It's more than likely I'll ride in a supporting role for Chris," Wiggins said at the presentation of the Tour's centenary edition 2013 route in Paris yesterday. "It was always about winning one Tour de France. I've done it and I'm very proud the way I did it. I want to be in a successful team and if that's Chris [as leader] then so be it.

"My priority is the Giro d'Italia. It's become apparent that it's very difficult to compete in two grand tours and so it's very likely I'll be there [in the Tour] in a helping capacity."

Wiggins did insist – jokingly – that "he [Froome] will have to grow some sideburns though", a reference to his own trademark muttonchops that became a familiar sight to British sports fans this year as Team Sky took a stranglehold on the Tour barely a week into the 21-day race.

Wiggins' supremacy last July was such that it will be hard to imagine a switch in roles for the British duo between team leader and domestique de luxe, as cycling calls the top "helper", but it would boost both Wiggins' personal ambition and Sky's chance of a repeat victory.

Should Wiggins win in the three-week Italian race – which he led for one day in 2010 – it would be a first for Great Britain. The inclusion in the Giro next year of a 53km individual time trial – unusually long for the Italian race and Wiggins' strongest suit – makes it even more attractive for him. Racing the Giro flat out, though, would make it almost impossible for the Londoner to dispute the Tour de France a month later.

Alberto Contador, cycling's top stage racer, was the last to try, last year. He won the Giro, but finished fifth in the Tour. Other Grand Tour winners, such as Cadel Evans and Denis Menchov, have tried the double and failed even more dismally.

Hence the increasing likelihood that Froome, rather than Wiggins, will step up in the 2013 Tour, and after the route for next July was revealed this week it became increasingly probable.