Former World No.1 Ana Ivanovic scored a comprehensive 6-1, 7-6(5)  victory over Ayumi Morita and advanced to the pre-quarterfinals of the 2011 Mercury Insurance Open, a WTA premier event being played here in Carlsbad, San Diego.

Ivanovic, who lost her previous battle with Morita last week in Stanford, came out all guns blazing in yesterday's match and reigned supreme with a straight sets win. Ivanovic was later joined by fourth seed Shuai Peng of Chinese Taipei, who humbled Australian Anastasia Rodionova 6-1, 6-3 in just 67 minutes of play.

Eighth seed Daniela Hantuchova also scored an identical 6-1, 6-3 win over Czech Barbora Zahlavova Strycova to reach the Round of 16. Hantuchova has one title from 2011 season and boasts of several confidence boosting wins over top players like Caroline Wozniacki and Venus Williams, whom she beat on grass in Eastbourne.

No.12 Sabine Lisicki, a semifinalist at Wimbledon this year, also advanced with an easy 6-1, 6-2 win over Japanese veteran Kimiko Date-Krumm. No.15 Sara Errani also made it to the last 16 with a confident 6-3, 6-2 win over American vania King.

In the day's biggest upset, German star Julia Goerges, seeded 7th here in Carlsbad, bowed out of the event with a shocking 6-3, 7-5 loss handed by American teenager Sloane Stephens. 

"I was just playing my game and going for it the whole match and obviously it's not working well right now," Goerges said. "I have to give all the credit to Sloane. She didn't give me any free points. But the way I was hitting the ball still felt good to me. I lost the match, but it was the right way for me to play."

Other notable winners of the day were Vera Dushevina, Coco Vandeweghe, Alberta Brianti, Christina Mchale, Virginie Razzano and Jie Zheng, who ousted ninth seed Roberta Vinci in straight sets.