Tennis star Serena Williams is over in the UK to play in Eastbourne's Aegon International and revealed the mystery illness she suffered earlier this year almost killed her.

"I'm so excited to be back," she told the BBC. "I was on my death bed at one point -- quite literally."

The four-time Wimbledon champ claims no one is sure how the illness began, but said it may have started from a cut on her foot.

"To this day I don't really know the full details of what happened," she said. "I was with my nephew and my hitting partner and we were just leaving a restaurant. I was walking and just felt something. I kept walking and it was definitely glass there. There was a massive puddle of blood. I ended up fainting and needed stitches in both feet."

It was then that the injury took a life-threatening turn.