World No. 6 Serena Williams withdrew from her Rome Masters semifinal against Li Na with a back injury on Saturday, sending the Chinese player straight into Sunday's final with Maria Sharapova.
"I had some problems with the lower back earlier [this] week," Williams was quoted as saying by the tournament website.
"It was feeling a little stiff and I don’t think this is the right moment to force [it]."
Williams, who won the Madrid Masters earlier this month, announced she would be taking a break ahead of French Open starting on May 27.
"There is a huge schedule coming up and when [there is] a little pain you can't, you just want to compensate and I have had a long treatment for the last couple months."
Former world No. 1 Sharapova is the reigning champion in Rome after defeating Australia’s Samantha Stosur 6-2, 6-4 in last year’s final.
