PARIS, May 21 (AFP) - Pete Sampras has done all there is to do in tennis - and more than most players could even dream of. He's been number one for a record six years and he's won 11 Grand Slam titles. The problem is, he has never won a French Open title. "It's my biggest challenge of my career at this stage," he admitted in Dusseldorf, where he was competing for the United States in the World Team Cup. "I've won everything except for the French and it would be the ultimate in my career to win that. "I know that and it's not going to be easy, but a challenge is something I need in my career right now. I'm going to look at these two weeks coming up as the biggest challenge of the year, and for my career, so I'm going to fight as hard as I can fight and give it my best shot." Sampras has not yet managed to adapt his usual attacking game to the patience he needs on clay at Roland Garros, and the closest he has come to the title was a semi-final appearance three years ago. "There are so many variables to playing on clay," he said. "For the French, it can take the weather. If it's nice and hot and dry it can really help out my game, but even if it's cold and wet you still need to find a way to win. "The problem for me on clay is that if I'm not serving well and I have to stay back, then I start pressing and start missing. I can really dig myself a hole. "The main focus for success on clay is my serve. If I can serve well and get some free points that way and really try to stay in control but be aggressive, that's how hopefully one day I'll win the French, by coming in. I'm not going to win it staying back." Although patience is needed, and success invariably comes to those who grew up on the surface and are happy to rally all day long, Sampras insists he can only compromise his style so far and no further. "I can stay back with the guys," he said, "but in the course of a long match it's not the way I'm going to win. I'm going to win against a clay court specialist by coming in, doing some chipping and charging and really trying to use my whole game. I'm not going to be a kamikaze and come in on anything, but it's picking my spots and being smart." This has not been the best of years for the American, who opens against Juan Antonio Marin of Costa Rica when the tournament starts on Monday. He put so much effort into ending last year at number one that he came close to burn-out and decided to miss the Australian Open. Now, he's still playing catch-up with himself. There are two ways to look at his lack of matches this year. One is that he is fresher than most of his opponents. The other is that he is lacking match practice. "It's a little bit of both," he agreed. "By not playing much I'm fresh mentally and physically, but from a tennis standpoint my game has been a little bit up and down because I haven't played many matches. So you've got some pros and cons there. "But I feel I'm pretty fit at the moment. Matches is what I need, and I've gotten that in Dusseldorf. I feel like endurance-wise I'm fine. It's just a question of getting into a rhythm and getting my game in synch, which I haven't really felt this year. Playing this week really helps my confidence, and leading up to the French confidence is what you need. "I really think I've found my range this week. I'm hitting the ball much better than I was in Rome. I like where I'm at at the moment." Sampras is not taking his preparation to extremes. Ivan Lendl never won Wimbledon, and it became an obsession. The Czech player dedicated his entire year towards a goal that was never to be. Sampras won't take it that far. "I'm not going to obsess about the French," he stressed. "You look at someone like Lendl who changed his schedule and changed his racquets. For me, my goal this year is to try to enjoy it and not stress out over the fact I haven't won there. I'm at the stage of my career now where I just want to enjoy these last three or four years or however long I play." Whether he succeeds and finally lifts the trophy or not depends largely on the weather being dry and the courts hard and fast. But he does give himself a chance. "It's a cliche, but it really is one match at a time, because at the French there are so many dangerous floaters that each match is just one you want to get through. I wouldn't consider myself a strong favourite, but I'm in contention."  