London, England -- (Sports Network) - Executive chairman and president of the ATP Etienne de Villiers announced on Thursday that he will not renew his contract at the end of this 2008 season.

Executive chairman since June 2005, de Villiers has overseen the most extensive set of changes to the ATP since its inception in 1990.

The changes, which will see $1 billion of new investment into the ATP, include record-breaking levels of prize money for players, new, world-class tournaments, an enhanced, healthier calendar structure, unprecedented levels of promotional spending and a new brand look and identity designed to make the tour more fan-friendly.

"I was tasked by the ATP board, three years ago, to create a vision that would involve bold changes for our sport," de Villiers said. "I believe that has now been achieved."

"I leave knowing, without doubt, that finally our players, tournaments and above all our fans have the foundations of a world-class sport they truly deserve."

De Villiers will fulfill his current three-year term as executive chairman, a term that ends in December.