Chris Froome not unbeatable says Alberto Contador, as pair set to face-off at Vuelta a España

Alberto Contador (Tinkoff) says that Tour de France champion Chris Froome (Team Sky) is not unbeatable in the Grand Tours, as both prepare to go head-to-head at the Vuelta a España later this month.

The Spaniard, who withdrew from the Tour after two crashes, made a winning return to stage racing at his home race the Vuelta a Burgos last week, as Froome competes at the Rio Olympic Games.

>>> Rio 2016 Olympic Games men’s time trial start list

And while Froome will be looking to add to his Tour triumph as well as a potential gold in the time trial in Rio on Wednesday, Contador will be looking to rescue his season with a win at the Vuelta.

No-one was able to match the Briton during the Tour de France, but Contador says Froome will not be unbeatable in the year's final Grand Tour, but it will be difficult to match the power of his Sky team.

"For me... it is more Sky than Froome [that is unbeatable]," Contador told Marca.

"Froome is obviously a very strong rider in both the time trial and on the climbs, but any rider can have a bad day. When you have a team where everyone can be a leader that makes it more difficult [for me]."

33-year-old Contador will be eyeing a fourth win in his home Grand Tour, while Froome has never managed to take the top step, with his best results second place in 2011 and 2014.

Both will face further competition from the likes of Nairo Quintana (Movistar) who is set to return to racing at the Vuelta.

Becoming a trademark of the race over recent years, the route looks exceptionally difficult with 10 summit finishes, suiting the pure climbers.

"The Vuelta is not the easiest of the three [Grand Tours]," Contador said. "We are already seeing that there will be a great line-up this year with riders like Froome, Nairo, Valverde, Landa... The route has surprises for everyone. Each year that seems to be exceeded."

Contador looked to set to retire at the end of the 2016 season with the folding of his current Tinkoff team, but had a change of heart after winning the Tour of the Basque Country in April.

He looks set to sign with Trek-Segafredo for the next two years, although that has yet to be confirmed by the team. While Contador remained coy over the potential transfer, he wasn't quiet about voicing his ambitions of winning a third career Tour de France title before he calls it a day.

"What Trek team? I don't know anything yet of this signing, so we can't announce when this addition will be.

"It's clear for me: the Tour de France next year. It's my main goal. I think I have condition to do it.

"But before arriving there, I still have other challenges to achieve. It may not be in Rio, but in the Vuelta a España."