Gustavo Kuerten is currently preparing to compete in next month’s Davis Cup. His 2007 ATP record isn’t too hot (his current record is 2-6), and he’s getting beef from naysayers breathing down his back.
Leave him alone and let him play on the tour as long as he wants. He’s enjoying himself, and has used his celebrity into founding a non-profit and starting a clothing line. He’ll quit when he’s ready.