Serena Williams revealed Thursday that she was battling flu after needing three sets to see off Swiss outsider Timea Bacsinszky 4-6, 6-3, 6-0 to reach a third French Open final.

The world number one looked distressed through large parts of her semi-final on a hot Court Philippe Chatrier, wrapping herself in ice towels between changeovers and walking wearily around the arena.

But remarkably she reeled off the last 10 games to reach Saturday's final where she will face Lucie Safarova for a third Roland Garros title and 20th career major.

"I have never felt so sick," 33-year-old Williams told US broadcaster ESPN.

"I caught the flu after my third round match and have been struggling ever since.

"I never thought I could win and I didn't want to go to a third set.

"But I thought that if I was going to lose I had better go for winners. I was so tired and the next thing I knew I was in a third set. I don't know what happened."

On her prospects for Saturday's final, she added: "I just hope I can get better from here."

The 25-year-old Bacsinszky, who was a break to the good in the second set before seeing her opponent sweep the last 10 games, said she tried not to let Williams's problems affect her.

"I have no idea how fit she was, I tried to forget that and just push myself," said the Swiss player who was working in hotels and restaurants just two years ago during an injury-enforced absence from the sport.

"It's only a tennis match. She was better and pulled out a great match.

"Whether she was struggling or not struggling, I was just focussed on what I was doing."
Source: AFP