Cycling: Chris Froome takes on the king of Spain in his own backyard

Contador is back today after a two-year drugs ban – and there is only one man he fears. By Alasdair Fotheringham

Team Sky's third and final Grand Tour challenge of 2012, the Tour of Spain, starts today in Pamplona, and it is a credit to Sky's track record this season that the British squad are considered the foreign rivals most likely to wreck the fiesta for Spanish cycling fans and their home idol, the hugely popular – if controversial – Alberto Contador.

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Unlike the Tour de France, which has not had a home winner since 1985, La Vuelta is very much a national affair. Eight times in the last 12 years, a Spaniard has raised his arms on the final podium of the three-week stage race in Madrid's Paseo de la Castellana, and almost half the 66 editions since the first in 1935 have gone to a locally-born rider. Today sees Contador, back from a two-year suspension for doping, make his return to Grand Tours. And the Madrileno has no intention of coming back quietly. Anything less than a second overall victory in his home race will be viewed, almost certainly by himself, as a failure.

Before his ban, Contador dominated three-week stage racing with almost frightening ease. Although he was stripped of a Giro d'Italia and a Tour de France title, the Spaniard still has two more Tours, a Giro and a Vuelta in his palmares, more than any other currently active rider. Given the controversial nature of his ban, the Spaniard, who insists he is innocent, has a huge point to prove. And the Vuelta, at least this year, is his one chance to prove it.

Contador tested positive in 2010 for the steroid clenbuterol, in a quantity 40 times below the minimum required for anti-doping labs to report. But a positive is a positive, however you look at it, for all Contador's claims that the clenbuterol had come from a contaminated steak.

Whatever the rights and wrongs of the case, Contador is widely expected to take his sporting revenge in the Vuelta. "He will win it by an entire day's margin," predicted Eddy Merckx, cycling's greatest ever rider, in February. Contador has taken the challenge very seriously. Whilst cycling's other top names were battling in the Tour, Contador was on a full-scale reconnaissance of the Vuelta's route, including riding up every single mountain-top finish.

No fewer than 10 of the race's 21 stages end on top of some kind of climb, from the ultra-steep, kilometre-long Mirador de Ezaro in one of Galicia's remotest corners to the Bola del Mundo, a 2,241-metre-high monster climb ending on a 3km cement track where the riders' wheels will barely have enough grip for them to accelerate.

For a top climber like Contador, the route looks more than suitable. But as the Spaniard said yesterday, although there are other big names in the Vuelta, Sky's Chris Froome is the one that he fears the most.

"There are three former winners of Grand Tours here [Alejandro Valverde, Denis Menchov and defending Vuelta champion Juan Jose Cobo] and they will be serious rivals. But Froome is the one that sticks out the most," Contador said. "Froome could be the most dangerous because he's also a good time triallist and has a very strong team. He could have won the Vuelta last year and he was the strongest rider in the Tour de France, although it's impossible to say if he'd have won because [winner and team-mate Bradley] Wiggins was strong in time trials."

Froome's second place in the Vuelta last year was a breakthrough result for the Kenyan-born Briton. Since then he has also ridden the Tour de France with Sky, finishing second behind Wiggins, which confirmed that the 2011 Vuelta ride was no fluke.

At this year's Vuelta, while Sky's morale is sky high after the Tour and their series of earlier triumphs this season, taking on Contador, on home soil to boot, is a challenge as big as they get in cycling.

"I'm not afraid of him, and he's got no reason to be afraid of me," Froome said. "We've both got a job to do. My aim is to continue the team's successful season to date and maintain the momentum we've had so far."

When it comes to keeping that winning feeling in Team Sky, if Froome wants to take and retain the leader's red jersey, it will almost certainly involve striking hard early in the race.

After such a long time without racing, Contador has admitted that he will be at his most vulnerable in the first week of the Vuelta, as he gradually polishes his form. "But by the third I hope to be ahead of my rivals and beating them," he said. "That is the idea."

There are plenty of chances for a skilled climber like Froome to get ahead of Contador in the first week. As early as Monday the race tackles the Arrate climb and on Tuesday there is another difficult ascent, to the Cruz de la Demanda.

"It will be a difficult race to calculate your strength in," Contador said. "There will be room for serious attacks from the word go; it won't be like the Tour de France."

In terms of the final result, though, with Sky fielding one of the top favourites yet again, whether La Vuelta turns out like the Tour remains to be seen.