With the U.S. Open beginning tomorrow, I thought it important to mention that this is the first year the Open or any grand slam event will be using instant replay. Players will have two “challenges” per set and an additional challenge for any tiebreakers, as is done similarly in football, which cannot be carried over from one set to another. If a call is overturned because of a challenge, that play does not loose the challenge.The method has been used in a number of tune-up tournaments leading up to the Open and seemed to work pretty well. There seems to be a general consensus among the tour players that this is a good thing, especially following a few particularly bad calls during huge points in the past few years.I think it is also a good thing. Dealing with bad line calls is a skill that tennis players are taught, but it is not nearly as much a part of the game as say expanding and shrinking of a strike zone in baseball. Different baseball umpires have different sizes of strike zones, and pitchers can generally expand the strike zone over the course of a game with good control (e.g. if they keep hitting the corners, the corners will move outwards and they “get the call”). Likewise, pitchers will poor control won’t get the benefit of the doubt on a close pitch and the strike zone can shrink. Umpires can also alter their strike zones based on their relationship to the pitcher or the batter; arguing balls and strikes tends to move the strike zone in the opposite direction of where you want it to go. Calling the lines in tennis doesn’t have nearly the same nuance, and I am not really sorry to see it go.While we’re at it: My U.S. Open picks.Predicted men’s final: Federer over Nadal in 5 (shocker!)Whom I’m rooting for: Andre Agassi (in a sweet farewell) and James Blake (he is in the top 5 now and its about time he breaks into the semis).Predicted women’s final: Sharapova over Henin-Hardenne in 2Whom I’m rooting for: Maria Sharapova (she’s better than her record of only one grand slam win) and Martina Hingis (I’m a sucker for comebacks)