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AP Argentina's Juan Martin Del Potro returns a shot to Ryan Harrison in the third round of play at the 2012 US Open tennis tournament, Friday, Aug. 31, - Photo

Argentina's Juan Martin Del Potro returns a shot to Ryan Harrison in the third round of play at the 2012 US Open tennis tournament, Friday, Aug. 31,

Friday August 31, 09:11 PM
Argentina's Juan Martin Del Potro returns a shot to Ryan Harrison in the third round of play at the 2012 US Open tennis tournament, Friday, Aug. 31, 2012, in New York. (AP Photo/Paul Bereswill)