Victoria Azarenka will take on Maria Sharapova in the quarter-finals of the Internazionali d'Italia following a three-set win over Irina-Camelia Begu.
Azarenka overcame a second-set glitch to down Begu 6-4 5-7 6-1.
The Belarusian served for the match in the second set, but was broken twice in succession as the Romanian squared the contest.
But the former world number one broke three times in a row in the decider to reach the last eight.
Earlier two-time champion Sharapova had seen off qualifier Bojana Jovanovski 6-3 6-3.
"I just had to be very patient and solid," Sharapova said. "I had a tricky opponent and not easy conditions - the wind was pretty swirly out on the court, so I just had to stay steady.
"Despite a couple of breaks back and forth in the second set, I was really happy to finish so strongly."
With top seed Serena Williams withdrawing from her match with Christina McHale because of an elbow injury, third seed Sharapova is among the favourites to lift the trophy alongside second seed Simona Halep, who dispensed of Serena's sister Venus.
Halep capitalised on an error-strewn performance from 14th seed Williams to cruise to an emphatic 6-2 6-1 success in just over an hour and set up an all-Romanian quarter-final with Alexandra Dulgheru.
Dulgheru overturned deficits in the first and second sets to stun eighth seed Ekaterina Makarova 6-4 6-3.
There were no such problems for Madrid Open champion and fourth seed Petra Kvitova as she cruised to a 6-3 6-2 triumph over 16th seed Jelena Jankovic to set up a last-eight clash with Carla Suarez Navarro following her gruelling battle with Eugenie Bouchard.
Suarez Navarro, seeded 10th, squandered four match points in a final-set tie-break and saved one held by sixth seed Bouchard, before taking her fifth to progress 6-7 (2-7) 7-5 7-6 (9-7) in over three hours.
Daria Gavrilova will play McHale after a 6-4 7-6 (7-0) win against Timea Bacsinszky.