Jan Ullrich has promised Lance Armstrong that he will do everything he can to stop the American winning a seventh Tour de France this summer.
Germany's Jan Ullrich won the Tour de France in 1997
Ullrich believes Armstrong's decision to retire after the July showpiece will set up a classic battle.
"I am not interested in finishing second," he said.
"I couldn't be more motivated. I'm working like mad to be in top
condition and I suspect it'll be the same for him in his last Tour."
Armstrong has won a record six successive Tours and will be determined to end his career with another title in July.
With his retirement now imminent, there has been plenty of speculation as to who will step into Armstrong's shoes.
Italy's Ivan Basso, who won the best young rider jersey in 2002 and came third last year, and 2004 Giro d'Italia winner Damiano Cunego are all predicted to shine in the future.
But for this year's race, Armstrong believes that it will be 1997 winner Ullrich who will be his main rival.
"I always consider the main rival to be Jan Ullrich," said Armstrong.
"He looks to be much better than he's ever been this time of year, so it could be an exciting Tour this year as far as that goes."