Paris - Increased suspense, a boom in television ratings and happy sponsors left Tour de France chief Christian Prudhomme in a buoyant mood two days prior to the end of this year's race. But with the ever-present threat of cheats lingering, the Frenchman knows it is far too early to talk of a definitive turnaround for the sport. After years of controversy the reputation of the race was tarnished by a minority of drugs cheats. But compared to recent scandals, this year's Tour, so far, has got off comparatively lightly. Spanish duo Manuel Beltran, of Liquigas, and Barloworld rider Moises Duenas joined Italian star Riccardo Ricco in leaving the race early after testing positive for the banned blood booster EPO (erythropoietin). On Sunday, it was revealed that Dmitri Fofonov, a Kazakh who rides for Credit Agricole, had been suspended by his team after testing positive for a banned stimulant. For some, it means the race will never be 100% clean. For others, it has shown that "more effective doping controls", according to French anti-doping chiefs, are starting to act as a real deterrent. Yellow jersey Prudhomme took over as chief in 2006, just in time to announce that Italian Ivan Basso and Germany's Jan Ullrich would not start because of their alleged links to the 'Operation Puerto' doping scandal in Spain. Twenty two days later, after Floyd Landis had won the yellow jersey, it was revealed he had tested positive for testosterone. Despite the Ricco scandal - the three other positive controls were comparatively low key riders - Prudhomme believes the threats made prior to the race by France's national anti-doping agency, the AFLD, had the desired effect. "When you find three or four cheats out of a total of 180, then we have to be satisfied," he said. "We can't have a complex about getting rid of these kinds of people. What we could be ashamed of is not finding any." Due to an ongoing feud between world cycling's governing body the UCI and major race organisers, the year's Tour was held under the auspices of the French cycling federation. The anti-doping controls were handled by the AFLD, which came into the race declaring war. Biggest sensation Beltran, a former teammate of seven-time winner Lance Armstrong, was the first to leave the race after testing positive for EPO. Compatriot Duenas then followed, but it was the snaring of Ricco - this year's Giro d'Italia runner-up who won two climbing stages on the Tour - which caused the biggest sensation. Ricco spent a night in French police custody and, despite medical products and paraphenalia being discovered in his hotel room, he told French police: "I did not take EPO. All the products that I've used were prescribed to me either by the Spanish doctor who works with my team, although I don't know his name." Before the first stage in Brest on July 5, blood samples were taken from all 180 riders, complementing some 80 random tests on potentially suspect riders during the month of June. Both Beltran and Ricco were snared when their suspect blood profiles prompted the AFLD to test urine samples from the pair, thus confirming earlier suspicions. Duenas was caught by one of the random tests on the race. The good news for Tour chiefs, and for cycling, was AFLD chief Pierre Bordry's assessment after all 180 blood samples were analysed. "Most of the samples we've dealt look normal. It appears that efforts are being made, and that the pressure we've applied has had an effect," said Bordry. Given the apparent efficiency of the AFLD's tests, more positives may emerge. But for now, Prudhomme - underlining the lack of spectacular individual performances this year - isn't too concerned. "I'm happy that the whole anti-doping effort has made such progress," he added. "I think we've seen on this race that the differential between those who cheat, and those who don't has reduced dramatically."