PARIS (AP) -- Two-time Tour de France champion Alberto Contador was busted for doping this year. Lance Armstrong is under new scrutiny for alleged cheating. Less well-known riders on teams with strong anti-doping policies were making their marks and getting some glory.

Bit by bit, the fight against drugs cheats in cycling was advancing.

The 99th Tour starts on Saturday in the Belgian city of Liege, and years of image-scarring doping scandals have cycling authorities ready to combat threats to the sport's greatest race.

With an expanding anti-doping toolbox, the International Cycling Union (UCI) hopes the culture of cheating that has been a constant in the sport for generations is finally headed for the history books.

"Cycling is in the process of changing," UCI chief Pat McQuaid said this month. "I will never say that we have completely got rid of doping from the sport - I don't think that's possible in any sport - but I will say that we are changing the culture."

The Tour had no major doping scandals last year. But the previous year had a big one: Contador tested positive for the stimulant clenbuterol in 2010 on his way to a third victory. It wasn't until last February that he was stripped of his title and given a two-year ban that expires after this Tour.

Authorities are still battling the remnants of doping, when testing was much less stringent. This month, the U.S. Anti-Doping Agency accused Armstrong - the retired former superstar of cycling - of using performance-enhancing drugs and other banned doping methods to win the Tour a record seven times from 1999 to 2005. Armstrong denies doping and notes he has never failed a drug test.

Armstrong's longtime coach, Johan Bruyneel, has been also targeted in the USADA case. Bruyneel, now the RadioShack Nissan Trek manager, says he'll skip the Tour so as not to be a distraction for his team and the race.

The UCI conducted more than 13,100 urine and blood tests last year, and through last May had carried out about 5,900. By comparison, more than 6,250 samples are to be tested at the Olympics and Paralympics in London this summer.

The UCI's main anti-doping thrust is its "biological passport" program, which collects samples to track parameters of athletes' blood levels over the long term and keeps watch for unusual fluctuations as signs of possible doping.

The program has been in place for four years, but only a handful of anti-doping cases have been brought based on it. UCI doctor Mario Zorzoli said a small number of riders with suspicious readings have been tested dozens of times, though he and other UCI officials declined to say who those riders were.

The passport has had a "deterrent effect," Zorzoli said at a UCI news conference this month. "It's clear that we have fewer suspicious cases, and the cases we do have are less suspicious than the ones before."

David Howman, director-general of the World Anti-Doping Agency, credits the UCI for doing "a lot on anti-doping. They do more than most and probably they have good reason for that."

But in an interview with The Associated Press, he also questioned the effectiveness of the testing. Much of the recent concern about doping has been about so-called "micro-dosing," in which athletes use tiny amounts of banned substances but still get a kick to performance - and evade detection.

Howman pointed to "those very sophisticated dopers who seem to be going below the detection radar and we have to do something about that, and we are trying."

In the end, sport officials like those at UCI can only do so much - and the athletes need to make good choices, he said.

"I think sometimes you have got to go back and say the responsibility for making sure your sport is clean rests with the athletes, and those who advise them - not those who actually manage the sport itself," Howman said.

He and McQuaid both pointed to the victory of Ryder Hesjedal at the Giro d'Italia last month as a sign of cycling's new times. The Canadian rides for Garmin-Barracuda team, which has been vocal in its opposition to doping.

Pointing to other clues, McQuaid noted that former track racer Geraint Thomas of Britain kept up with the pack and finished the "very, very difficult Giro ... that wouldn't have happened" if doping was widespread in the pack.

And in the not-so-distant days of more widespread doping, a team leader would have six or seven teammates beside him on a tough mountain climb, but rarely anymore, McQuaid said.

"Little signs like this: When you add them all together you see that there's a change in the behavior of the athletes, and it's a change for the good," he said.

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