Janko Tipsarevic advanced to the fourth round of the U.S. Open when ninth-seeded Tomas Berdych retired in the second set Saturday. The 20th-seeded Tipsarevic was leading 6-4, 5-0 when Berdych decided he couldn't keep playing with the injury to his right, serving shoulder. Tipsarevic upset Andy Roddick in the second round at the Open last year. More...