"The ATP Challenger Tour, known until the end of 2008 as the ATP Challenger Series, is a series of international men's professional tennis tournaments. The top tier of men's tennis is the ATP World Tour, Challenger Tour events are the second highest level of competition, and the Futures tournaments on the ITF Men's Circuit are the third and final tier of international professional competition. The ATP Challenger Tour is administered by the Association of Tennis Professionals."@en .