Serena Williams reached the last eight of the Italian Open with a 6-3 6-3 win over Shahar Peer, the third time she has beaten the Israeli this season.
Williams has had the better of Peer three times this season
Williams, who also beat her in Miami and Australia, now faces Patty Schnyder who beat Samantha Stosur 6-4 6-4.
Williams's win began with five breaks of serve in a row before a marathon final point finally earned her victory.
"It wasn't as easy as I expected. We had a lot of deuces and the last point was really long," said Williams.
"This was a good test, she gets a lot of balls back and plays well on clay. It was a good match for me."
Jelena Jankovic survived being broken three times in the second set for a 6-4 7-5 win over Alona Bondarenko.
Her next opponent will be Elena Dementieva, who earned her last eight spot when opponent Nadia Petrova was forced out with a back injury when trailing 4-3.
Petrova, who injured herself in training, said: "It had been getting better, but when I ran for a wide ball I felt a sharp pain. It just kept getting worse."
Daniela Hantuchova beat Russian seventh seed Anna Chakvetadze 6-2 6-3 while last year's runner-up Dinara Safina beat Kateryna Bondarenko 6-2 6-3, to set up a last-eight match with Svetlana Kuznetsova.
The second seed had to work harder than she would have expected as she beat Yulina Fedak 7-6 6-1.
Kuznetsova is the highest-ranking player left in the tournament after the elimination of top seed Amelie Mauresmo.
But she twice failed to serve out for the first set and was 4-1 down to the world number 138 in the tiebreak before recovering and breezing through the second set.