London - Serena Williams said she was "heartbroken" by having to retire from her Wimbledon doubles with sister Venus because of a viral illness which saw her close to fainting and in tears.
VIDEO: Ailing Serena forced to withdraw
Serena, the 32-year-old world number one singles player, called the doctor to Court One just after she and Venus had warmed up for their second round match against Kristina Barrois and Stefanie Voegele.
But after serving up four double faults, a clearly distressed Serena, who was unsteady on her feet, was led by the hand by Venus off court where the sisters then conceded the tie at 3-0 down.
"I am heartbroken I'm not able to continue in the tournament," Serena said.
"I thought I could rally this morning, because I really wanted to compete, but this bug just got the best of me. I want to thank my sister, Kristina, Stefanie and our teams for their support.
"We were all looking forward to a great match. From the bottom of my heart, I thank all of the fans for their cheers and understanding. I look forward to returning to Wimbledon next year."
Venus expressed sympathy for her younger sister.
"Unfortunately Serena has been feeling unwell for the past few days and she just couldn't play to her potential today," Venus said in a statement.
"I'm really proud of her for trying because we just love playing doubles together. We are looking forward to coming back to Wimbledon next year."
Serena was in tears courtside as she consulted with the doctor and physio before the tournament referee and supervisor were also called out in a reflection of her status in the sport.
After a 15-minute delay, during which she also had her blood pressure monitored, the match got underway but it was clear it would be a brief affair.
Umpire Kader Nouni, having already come down from his chair to talk to the Americans, announced that Serena was retiring from the match through illness with the sisters trailing 3-0.
Serena had been knocked out of the singles by Alize Cornet in the fourth round while Venus made the third round where she was defeated by Petra Kvitova.
The American has suffered health problems in the past, notably enduring life-threatening blood clots in 2011.