Williams and Sharapova progress
World No 1 Serena Williams continued her march towards a first Western and Southern Open title with a 6-2 6-2 demolition of 13th seeded Italian Flavia Pennetta.
The 17-time grand slam winner was joined in the last eight by second-seeded Romanian Simona Halep, who defeated Czech Lucie Safarova 6-4 7-5.
While Williams' brilliant resume includes 61 titles the Cincinnati hard court event is not on that long list and the 32-year-old American has set her sights on a adding it to her collection.
In five previous visits Williams has only reached the semi-finals twice with her best result coming last year when she let the title slip through her fingers losing in a third set tiebreak to Victoria Azarenka.
"I love coming here, it's fun," said Williams, who is a perfect 12-0 on American hard courts this season. "I like it because it's in America, as well, and it's so good to play some tournaments in the United States.
"Being an American, it just feels like you're at home. Even though it's not your home state it's your home country, so it's a great feeling."
Williams looked completely at home on Thursday and in control right from the start as she raced to a 3-0 lead in the opening set then cruised through the second after charging in front 5-0.
"I got an early break on and I just didn't let go," said Williams, who will defend her US Open crown later this month.
\"That's what I wanted to do, because she can try to come back. Even in the end she tried to make a comeback. But I knew I needed to kind of stay focused."
French Open champion Sharapova booked her quarter-final berth with a straight-sets win over Anastasia Pavlyuchenkova.
Fifth-seeded Sharapova, who now plays Halep in the semis, needed one hour and 58 minutes to get past her fellow Russian 6-4 7-6 (7/2).
No 4 seed Agnieszka Radwanska was in imperious form as she routed Sabine Lisicki 6-1 6-1, while Jelena Jankovic, the eighth seed, edged out Sloane Stephens 7-6 (7-4) 6-4.
Fellow Serb Ana Ivanovic, the No 9 seed, recovered from a second set wobble to see off Svetlana Kuznetsova 6-2 2-6 6-3.
Elina Svitolina hit back to defeat 15th seed Carla Suarez Navarro 4-6 6-4 6-4, while 12th seed Caroline Wozniacki beat sixth-seeded Angelique Kerber 7-5 6-2.