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Serena Williams of the United States cannot return the ball as she slips on the grass against Jelena Jankovic of Serbia during a first round match at the All England Lawn Tennis Club in Wimbledon, London at the 2012 Summer Olympics, Saturday, July 28, 2012.
WIMBLEDON, England—Serena Williams advanced to the second round at the Olympics on Saturday on the same Wimbledon court where she won her 14th Grand Slam title a few weeks ago.

U.S. First Lady Michelle Obama watched from the front row of Williams' box as the fourth-seeded American beat former No. 1 Jelena Jankovic of Serbia 6-3, 6-1 on Centre Court.

Williams is aiming for her first gold medal in Olympic singles; she has won two gold medals in doubles with big sister Venus.