At this time I would like to throw in the name of "Lew Hoad" - never knew who this guy was but again couple of other guys think he's pretty good - Rod Laver and Pancho Gonzales: if these guys think he's good - what does it matter what I think!
Excerpt from wikipedia:
"His first year as a pro was a series of head-to-head matches with the reigning king of professional tennis, Pancho Gonzales. Hoad won 18 of the first 27 matches, but Gonzales surged back to finally defeat Hoad by 51 matches to 36. Gonzales, whom some consider to be the greatest tennis player of all time, always maintained that Hoad was the toughest, most skilful adversary that he had ever faced. "He was the only guy who, if I was playing my best tennis, could still beat me," said Gonzales in a 1995 New York Times interview. "I think his game was the best game ever. Better than mine. He was capable of making more shots than anybody. His two volleys were great. His overhead was enormous. He had the most natural tennis mind with the most natural tennis physique."