Each day during the 2011 U.S. Open, coach Nick Bollettieri will discuss the most intriguing matches on the schedule and offer his predictions.

Rafael Nadal [2] vs. Andy Roddick [21] (Arthur Ashe Stadium, second match)

Nadal is 6-3 against Roddick and they split their two matches last year (Nadal won in the ATP World Tour Finals; Roddick won in Miami). I am so happy that Roddick is playing excellent tennis again at the U.S. Open. He now has one of—if not the—toughest tests on his hand: beating Rafael Nadal.

Roddick will need to have a big serving day, and he needs to continue to break serve at the pace he has done thus far throughout the tournament. He cannot get into long cross-court rallies with the Spaniard, otherwise Nadal will use his heavy-spinning balls to push Roddick back. Nadal will do what he does every time he takes the court, which is to compete harder than anyone else. He knows what he needs to do to win this match, and based on the way both men have played in 2011, I have to give the advantage to Nadal.

Nick’s Pick: Nadal in four sets.

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Andy Murray [4] vs. John Isner [28] (Arthur Ashe Stadium, first match)

Murray is 1-0 against Isner, with that win coming in the fourth round of the 2010 Australian Open. This match features one of the best servers in the game versus one of the best returners in the game. Isner will need to have one heck of a serving day to beat Murray, because the Scotsman is usually able to negate many players’ big serves. Isner should also try using a big kick serve to open the court and give him some free points.

I don’t feel Murray can stay back behind the baseline and win this match. He needs to stand closer to the baseline, otherwise Isner is going to use drop shots and big groundstrokes to control the court. The longer this match goes, the more it favors Murray. If Isner is to win, I think he’s got to do it in three sets or a quick four sets. I have to give the edge to Murray based on the way the two have played this year, but if Isner is able to grab control early, this could be an upset.

Nick’s Pick: Murray in four or five sets.

Nick Bollettieri of the IMG Bollettieri Tennis Academy has trained many collegiate and professional players, including 10 who reached the world No. 1 ranking.