Serena Williams cries after defeating Aravane Rezai in the first round at Wimbledon on June 21, 2011 in London, England

*Returning to Grand Slam action following a year full of health issues, Serena Williams beat France’s Arvane Rezai 6-3, 3-6, 6-1 at Wimbledon Tuesday — then began to sob.

After serving her 13th ace to close the match, Williams buried her face in her towel and cried from her courtside chair. She was still crying as she walked off the court.

According to the AP, the four-time champion fought through a mid-match slump before asserting command in the third set with her big serve and powerful groundstrokes.

Serena reacts to a play during her first round match against Aravane Rezai of France

That was enough to show why she is still considered a title favorite despite her long layoff after two foot operations and blood clots in her lungs.

Venus Williams (L) and Serena Williams conclude their training session on the Aorangi Practice court at the All England Lawn Tennis and Croquet Club ahead of the Wimbledon Lawn Tennis Championships on June 18, 2011 in London

Meanwhile, big sister Venus – the five-time champion who turned 31 last week – is returning to tennis after nearly five months off with a hip injury. After winning her first round Monday, she’s scheduled to play her second round match against 40-year-old Kimiko Date-Krumm of Japan on Wednesday.

Below, Serena’s emotional post-match interview.