Serena, who lost in singles Saturday, was given a blood pressure test by medical staff before the doubles match against Kristina Barrois and Stefanie Voegele even began as she struggled to hit shots and serves. Sitting in her sideline chair, Serena covered her face with her hands.
The match began after a 13-minute delay and, with Serena serving in the third game, she was hitting serves that bounced before reaching the net.
At love-40, chair umpire Kader Nouni took the unusual step of climbing down and walking over to ask Serena if she could continue. After nodding yes, Serena, who appeared glassy-eyed, then served another double-fault to trail 3-0.
Serena and Venus then walked to the sideline holding hands, and Nouni announced to the crowd: "Ladies and gentlemen, unfortunately, Miss Williams has to retire.''
The Associated Press contributed to this report.