Serena Williams of the U.S. competes in a women's singles match against Garbine Muguruza of Spain at the French Open tennis tournament at the Roland Garros stadium in Paris May 28, 2014.
Serena Williams of the U.S. competes in a women's singles match against Garbine Muguruza of Spain at the French Open tennis tournament at the Roland Garros stadium in Paris May 28, 2014. REUTERS

Finally, Serena Williams broke her silence about the viral illness, which made her retire in the women's doubles at Wimbledon, after serving four double faults in a single game.

The 17-time Grand Slam champion was with the former world no.1 also her elder sister Venus Williams. It was hard for Serena to stand properly, more so to hit the ball.

The 32-year old claimed that at that time, she was afraid and she did not know what she felt.

"It was interesting and I was scared after," Serena said. "I didn't realize how I felt until later. In the moment, I didn't realize how sick I was. It's weird but that's the fight in me. I never know when to say when," she added.

According to the tennis superstar, Venus told her to leave the match but she was hesitant.

"She kept saying, 'Walk off the court, I'm the older sister and I say you have to leave,'" the world no. 1 said. "I'm feeling really good right now and I'm happy to be here." Serena said she will undergo a series of tests at the end of the season.

"I was really ill," she said. "I got to thinking about a lot of things and because of family history, I'll get the tests done and we'll go from there."

In the past, Serena Williams missed a number of tournaments due to medical conditions.

In 2013, the same year that the tennis superstar completed a self-styled "Serena Slam" by winning four consecutive titles, Williams missed eight months of tour due surgery on her left knee. In 2010, a couple of days after winning Wimbledon, she cut her feet on broken glass while leaving a restaurant, which led to surgeries, complications and series of hospitalisations that led her off the tour for almost 10 months.