Serena, Sharapova again on Miami collision course

Li Na of China returns the ball to Carla Suarez Navarro of Spain at the Sony Open Tennis tournament in Key Biscayne, Miami, March 24, 2014. [Photo/icpress.cn]

MIAMI - World number one Serena Williams led a stampede of top seeds into the quarterfinals of the Sony Open on Monday but big sister and three-time Miami champion Venus could not join the party.

On a day that saw play interrupted by rain, it seemed nothing could stop the cream of women's tennis from rising to the top with Williams, a six-time Miami champion, Australian Open winner Li Na, third seed Agnieszka Radwanska, five-time runner-up Maria Sharapova and fifth seed Angelique Kerber all moving into the last eight.

But Serena's big sister Venus could not complete the Williams family double falling 6-1 5-7 6-3 to Slovakian 10th seed Dominika Cibulkova just as the center court clock was about to strike midnight.

While Serena Williams and Sharapova clashed in last year's Miami final there will be no championship rematch this Saturday with the American and Russian on the same side of the draw and closing in on a semifinal showdown.

After getting her title defence off to a slow start, Williams, who lives an hour's drive from the Crandon Park Tennis Center and considers the event her home tournament, stepped it up a gear against Coco Vandeweghe, sweeping past the young American qualifier 6-3 6-1 in 79 minutes.

"I was definitely happier today," Williams told reporters. "I was really struggling my first two matches, so I just wanted to have a better performance today.

"Going into the match I knew I could only do better. That kind of helped out, too."

Li was no less ruthless, the Chinese world number two demolishing Spain's Carla Suarez Navarro 6-0 6-2 in 61 minutes while Radwanska grinded out a 7-6 (5) 5-7 6-2 victory over Ukraine's Elina Svitolina.

Fourth seed Sharapova got a much-needed wake-up call after sleep-walking her way through the opening set before dispatching Belgian Kirsten Flipkens 3-6 6-4 6-1 while Kerber also needed three sets to get by Russian Ekaterina Makarova 6-4 1-6 6-3.

Former world number one and 12th seed Ana Ivanovic seemed headed for a quarterfinal berth after comfortably taking the first set against eighth seed Czech Petra Kvitova but fell apart after that, committing 11 double faults en route to a stunning 3-6 6-0 6-0 loss.