LONDON — After a three-year absence from Wimbledon, Juan Martin del Potro is making another strong run at a Grand Slam. Del Potro, the 2009 U.S. Open champion who has undergone three surgeries on his left wrist since 2014, beat fourth-seeded Stan Wawrinka 3-6, 6-3, 7-6 (2), 6-3 on Friday to reach the third round
