Lance Armstrong has hit back at Alberto Contador by describing the Tour de France winner's latest criticism of him as "drivel". The pair both race for the Astana team, and the rivalry between them was thinly disguised during this year's Tour, which saw Armstrong finish third.

The animosity finally boiled over into the public arena yesterday when Contador criticised the American at a press conference on his return to Madrid.

The Spaniard said: "My relationship with Armstrong is nil.

"He's a great champion, and he had a great race in this Tour, but it's something else on a personal level, where I've never had a great admiration for him, and I never will. On this Tour there have been more tough days in the hotel than in the race itself."

Armstrong, who returned to riding in January after three years in retirement, hinted at criticism of Contador's go-it-alone tactics during the race.

But today he made his feelings clear on his Twitter feed. The seven-time Tour champion said: "Seeing these comments from AC, if I were him I'd drop this drivel and start thanking his team. Without them, he doesn't win."

Armstrong then fired off another post. "Hey pistolero," he wrote referring to Contador's trademark victory salute. "A champion is also measured on how much he respects his team-mates and opponents. There is no 'I' in team'. What did I say in March? Lots to learn. Restated."

Armstrong's outburst is in contrast to his earlier praise of his team-mate's abilities, claiming Contador is so good the Spaniard would have beaten him in his own heyday.

"I think this year's performance would have beaten me in 2001, 2004 and 2005," said Armstrong. "Contador is that good, so I don't see how I would have been higher than that, even in the other years."

The rivalry between the two is likely to increase next year with Armstrong confirming last week he will leave Astana to head up a new RadioShack team next season. Contador is also set to move after hinting he was unhappy with Astana's refusal to back him as leader above Armstrong.

Race organiser Christian Prudhomme is relishing the prospect of a Contador/Armstrong battle in 2010.

"We need duels in sport, like Rafael Nadal v Roger Federer or Bernard Hinault v Greg LeMond," he said.

"Next year a team with Contador, another with Armstrong and another one with the Schleck brothers, Andy and Frank, would be sensational."