Pete Sampras believes tennis is free of performance-enhancing drugs now, as well as during his 14-year pro career that ended in 2002.
The winner of 14 Grand Slam titles says other than "a random case here and there" he doesn't see the top players engaging in doping.
All top tennis players are subject to being tested without warning.
Sampras spoke Monday night after playing doubles with top-ranked Novak Djokovic in the Los Angeles Tennis Challenge exhibition.
Last month, the International Tennis Federation banned 124th-ranked Barbora Zahlavova Strycova of the Czech Republic for six months for doping. She tested positive for the stimulant sibutramine last fall. She said the drug got into her system through a supplement and denied taking it to enhance her performance.