By Matt Majendie
BBC Sport in Liege
Heras was one of Armstrong's favourite team-mates
Roberto Heras has pledged to snatch the Tour de France yellow jersey in the Pyrenees from former US Postal team-mate and favourite Lance Armstrong.
A year ago, the Spaniard was coaxing Armstrong up the toughest ascents.
But following his switch to Liberty-Seguros, Heras is viewed by many as the major threat in the mountains.
"It'll be our time to attack," Heras told BBC Sport. "I aim to already be in contention then but, with the Spanish support, I plan to take yellow."
Heras added: "I can't wait for the mountains and the Pyrenees should suit us as a team."
The Spaniard is arguably the most naturally gifted climber among the Tour's 188 riders, along with countryman Iban Mayo - another overall threat.
And Liberty paid more than £1m to lure him away from US Postal.
Despite the high price and his £800,000-a-year salary, Heras is talking down his chances of maintaining yellow until Paris.
"I feel good but no better than previous years physically," he said. "But for once I now have an entire team behind me, doing what I want to do.
"If that doesn't inspire me on the climbs, nothing will."
Heras is being talked about as a possible title contender, although his major weakness - his time trialling - leaves him some way short of his rivals.
The final time trial on stage 19 could see him lose as much as three minutes to Armstrong.
He admits it is still a weakness, but added: "I'm not quite up to Lance's standard but my time trialling's getting better."
But the threat he poses is clear judging by the lengths US Postal went to keep him. Postal boss Johan Bruyneel described his eventual departure as a "bitter loss".
Despite that, Heras insists he has maintained a good relationship with his old team.
He said: "I left with good feelings but wanted a chance to test myself. I feel I have that and I feel the back-up is good. It will be good to show what I can do."