While reading the discussion about Coria's serving woes, it got me wondering if there's been any documented cases of pro tennis players with the "yips". Some athletes in other sports have developed mental barriers that kept them from doing the simplest things. I recall Steve Sax and Chuck Knoblauch, two baseball players with superior skills who went through periods where they weren't able to make the easist throws to first base. Golfer Bernard Langer went though something similar on short putts during the prime of his career. Anyone aware of this kind of thing happening to a pro tennis player?