Lance Armstrong will decide at the end of April whether to defend his Tour de France crown - but has pledged to go for a seventh title in 2005 or 2006.
Armstrong is the only man to win six Tours de France
The Texan has hinted he may not compete this year, and on Monday said he will decide after the spring classics.
"The deal was I was going to do the tour in 2005 or 2006," said Armstrong at his Discovery Channel team's launch.
At the moment I can't say if I'll take part. We're not ruling anything out, but will see at the time."
The 33-year-old looks set to compete in the Tour of Flanders on 3 April and Liege-Bastogne-Liege on 24 April.
Armstrong's major rival, Jan Ullrich, however, has dismissed speculation Armstrong will not ride this year's Tour de France.
But Ullrich, who could only finish fourth last year, told German television: "I don't really believe it.
"He will want to defend his title. I believe he still targets the Tour - if it wasn't his goal anymore, he'd stop."
Ullrich has one Tour win under his belt - in 1997 when Armstrong did not compete - and would prefer to have the American in the race.
He said: "It would be good for the sport and it would be good for me too.
"To win against the man to beat for the last six years is a great motivation and challenge especially to me.
"Final victory at the Tour de France is always very valuable, even without him, but it will count for more if he's there, that's for sure."
The Discovery Channel professional cycling team for the 2005 season:
Lance Armstrong (USA), Jose Azevedo (POR), Michael Barry (CAN), Manuel Beltran (ESP), Fumiyuki Beppu (JPN) , Volodymyr Bileka (UKR), Janez Brajkovic (SLO), Michael Creed (USA), Antonio Cruz (USA), Tom Danielson (USA), Stijn Devolder (BEL), Viatcheslav Ekimov (RUS), Roger Hammond (GBR), Ryder Hesjedal (CAN), George Hincapie (USA), Leif Hoste (BEL), Benoit Joachim (LUX), Jason McCartney (USA), Patrick McCarty (USA), Gennady Mikhaylov (RUS), Benjamin Noval (ESP), Pavel Padrnos (CZE), Yaroslav Popovych (UKR), Hayden Roulston (NZL), Jose Luis Rubiera (ESP), Paolo Savoldelli (ITA), Jurgen Van den Broeck (BEL), Max Van Heeswijk (NED).