WIMBLEDON, England — Returning to Grand Slam tennis after a year out with health problems, Serena Williams opened her Wimbledon title defense Tuesday by beating Aravane Rezai in three sets — then burst into tears on Centre Court.

After serving her 13th ace to close a 6-3, 3-6, 6-1 victory, Williams buried her face in her towel and sobbed from her courtside chair. She was still crying as she left the court, overcome with emotion after enduring a long layoff that included two foot operations and treatment for blood clots in her lungs.