Four-time champion Serena Williams has withdrawn from the Italian Open after suffering with an Achilles injury.

The 38 year-old was knocked out of the semi-finals of the US Open by Victoria Azarenka on Friday, and during the match she took a medical time-out early in the third set to have her left ankle re-taped. 

The former world No 1 said: “I regretfully must withdraw from the (Italian Open) due to an Achilles strain.

“I'm so humbled by the continuous support from my fans in Rome and I look forward to making my return soon.”

The Italian Open in Rome is due to start on September 14 in preparation for the French Open later this month. 

The clay event was rescheduled from May after it was affected by the coronavirus pandemic.