Andre Agassi significant championships. In 1998, Agassi began a rigorous conditioning program and worked his way back up the rankings by playing in Challenger Series tournaments, a circuit for pro players ranked outside the world's top 50. After returning to top physical and mental shape, Agassi recorded the most successful period of his tennis career and also played classic matches in that period against Pete Sampras and Patrick Rafter. In 1998, Agassi won five titles and leapt from No. 110 to No. 6, the highest jump into the top 10 made by any player during a calendar year. At Wimbledon, he had
Doping in tennis and International Tennis Federation (ITF) led a combined anti-doping initiative in professional tennis. Following the joint initiative between the ATP and WTA, the International Tennis Federation (ITF) became the sole governing body for professional tennis anti-doping initiatives in 2007, as the Association of Tennis Professionals (ATP World Tour) and Women's Tennis Association (WTA World Tour) moved towards a player-focused organisation and administrative role. Other bodies that regulate doping within tennis on a national level include the United States Anti-Doping Agency. In 1997, Andre Agassi returned a positive drug test for the use of methamphetamine. A joint investigation carried out by