Serena Williams celebrated a fifth Wimbledon women's singles title on Saturday and admitted she thought she'd never be a winner again after battling a life-threatening illness.

Williams, who now has 14 Grand Slam titles, was laid low by dangerous blood clots that kept her out of the sport for a year until the eve of last year's tournament.

But the American buried all those fears with a 6-1, 5-7, 6-2 win in the final over Polish world number three Agnieszka Radwanska.

“I can't describe it. I almost didn't make it a few years ago. I was in hospital and I thought I'd never be here again, so this makes it so worth it,” said Williams, the first 30-year-old since Martina Navratilova in 1990 to take the title at the All England Club.

“It's all the sweeter. I was so down but you never give up. You have to continue,” added Williams, who won her first Wimbledon title in 2002.

Radwanska, bidding to become the first Pole to win a major title, had been laid low by a respiratory illness in recent days but battled hard before losing.

It was her third defeat in three matches against Serena, but the first time she had taken a set off the champion.

“I am very proud to have got to the final. I am still shaking but I tried, it just wasn't my day,” said the 23-year-old, who was fighting back tears after the final.

“I have been unlucky here, playing in the wind and the rain, but I still played some great matches.”