Novak Djokovic double-faulted, then shook his right arm and grimaced. Seconds later Monday night, a weak serve produced a wince from the U.S. Open's defending champion, then was followed by a missed forehand that gave away a set - the first set dropped by Djokovic in the first round of any Grand Slam tournament since 2010. While he managed to emerge with a 6-3, 5-7, 6-2, 6-1 victory over Jerzy Janowicz of Poland, there were plenty of signs of trouble, starting with a visit from a trainer who massaged Djokovic's bothersome arm after only five games.
In its maiden match, Caroline Wozniacki—a two-time finalist here—beat Taylor Townsend in three sets, 7-5 in the third. Then young American Frances Tiafoe served for the match against John Isner but capitulated and fell 7-6 in the fifth set. Keep an eye on Naomi Osaka, an 18-year-old based in Florida who plays for Japan.
There will no longer be a time during the U.S. Open when all tennis matches will be canceled because of rain. On Tuesday, the USTA showed off the new retractable roof over Arthur Ashe stadium — the tournament’s largest venue for matches — which has 23,771 seats. The roof is made up of fabric covered with PTFE (polytetrafluoroethylene) and it sits on a 6,500-ton steel structure. The fabric “allows sun to reflect off the panels, making the stadium more energy efficient,” according to the U.S. Tennis Association, or USTA. It will also provide shade to people sitting in the higher sections, even when the movable parts of the roof are open. The roof, which cost about $150 million in privately funded