I personally do not bet on sports. However I have a good friend who is largely into sports betting, mostly basketball and baseball. Being a fan of many different sports, I would have to say that tennis is much easier to predict in comparison to other sports. Obviously upsets do occur in sports such as tennis. However there seems to be a number of factors that make tennis a bit more predictable...such as court surface, the schedule, and the fact that tennis is an individual sport. Obviously the court surface plays a major role. Nadal could be playing just about anyone in the world, and if it's on clay....it's almost impossible seeing him lose. Same with Federer at Wimbledon on grass (or just about any other surface). Secondly, players are constantly playing tournaments throughout the year, so it's quite easy to see when a player is hot (ie Blake and Ginepri during the US Open series last yr). Nobody probably would've predicted those two going so far at the US Open, however.....their results leading up to the tournament definitely indicated such a trend. Lastly, unlike team sports I think tennis is a bit more predictable. For example, in basketball Michael Jordan could have a heck of a game however if Scottie Pippen or Horace Grant didn't step up and play well....his team could STILL lose. On the other hand, in tennis if Federer's playing well.....he's almost certainly winning.