Serena Williams is confident she will be fit for the French Open after withdrawing from this week’s Italian Open in Rome.

The former world number one had been due to face older sister Venus in Italy on Wednesday but has been forced to pull out with a knee problem.

The 23-time Grand Slam winner has competed in just four tournaments this season and had to withdraw from both the Miami Open and Indian Wells earlier this year.

Williams, who has won three French Open titles, is hopeful the injury is not too serious and at this stage she expects to compete in Paris.

“I must withdraw from the Italian Open due to pain in my left knee,” she said, as reported by the WTA’s official website.

“I will miss the fans and competition at one of my favourite tournaments. “I’ll be concentrating on rehab and look forward to seeing you all at the French Open and next year in Rome.”

Williams is 13.00 to win the French Open outright. Defending champion Simona Halep has started to find some form after a tough start to 2019 and she is the current 4.50 favourite to win the French Open.

US Open and Australian Open champion Naomi Osaka is 13.00 as she seeks a third successive Grand Slam crown and 2016 winner Garbine Muguruza is 17.00.