Updated

Red-hot Serena Williams and former world No. 1 Victoria Azarenka secured berths in the semifinals, while two-time defending champion Maria Sharapova pulled out of her scheduled quarterfinal match Friday at the Italian Open because of a viral illness.

The world No. 1 Williams pasted helpless Spaniard Carla Suarez Navarro 6-2, 6-0, while the second-seeded former No. 1 Sharapova decided against playing seventh-seeded Italian favorite Sara Errani in a rematch of last year's French Open final, which was won by the tall Russian, as Errani received a walkover into the final four, where she'll take on the third-seeded Azarenka on Saturday at Foro Italico.

Sharapova reached the quarterfinals with a 6-2, 6-1 pasting of American Sloane Stephens on Thursday, but said Friday she was unable to continue because of a problem that started last week in Madrid, where she finished as the runner-up to the mighty Williams.

"I'm sorry for having to withdraw from the tournament this morning," said Sharapova on her Twitter account. "Didn't recover after being sick last week and it got me again last night."

Sharapova beat Chinese Li Na in last year's Rome finale.

Meanwhile, the reigning Wimbledon and U.S. Open champion and 2002 Rome titlist Williams, fresh off her clay-court title in Madrid, is now riding a career-best 22-match winning streak.

"I've been pretty consistent, and pretty healthy -- knock on wood," Williams said. "I feel great -- never felt better."

Williams' semifinal opponent will be surprising Romanian Simona Halep.

And the Australian Open champion Azarenka held off ninth-seeded former U.S. Open champion Samantha Stosur of Australia 6-4, 1-6, 6-3 in Friday's nightcap. The former French Open runner-up Stosur was the Rome runner-up to Sharapova two years ago.

The aforementioned Halep fought back to upend Serbian Jelena Jankovic 4-6, 6-0, 7-5 at this clay-court French Open tune-up. The former world No. 1 Jankovic is two-time titlist and former runner-up in Rome.