World No.3 Vera Zvonareva joined others seeded stars into the next round of the 2011 Mercury Insurance Open, a WTA premier event being played here in San Diego, California.

Zvonareva scored a comprehensive 6-4, 7-5 win over American veteran Jill Craybas to advance to the pre-quarterfinals. She was later joined by second seed Andrea Petkovic of Germany, who beat home favourite Alexa Glatch 6-3, 6-4.

No.3 Agnieszka Radwanska also made it to the next round with a hard earned 6-0, 7-6(4) win over British star Elena Baltacha.

The day mostly saw the completion of first round matches featuring several seeds as well. No.12 Sabine Lisicki, a semifinalist at Wimbledon this year, breezed past Hungarian Greta Arn 6-0, 6-2 in just 52 minutes of play.

No.11 Maria Kirienko also made it to the second round with an easy 6-3, 6-2 win over Canadian star Rebecca Marino.

"I was happy with my serve. I've been trying to improve my speed on the serve and it's getting better," Kirilenko said. "Of course she hit some aces today but I played well on my returns and also felt comfortable on my serve too. I was hitting some good drop shots too."

However, No.10 Flavia Pennetta wasn't as lucky as she lost her opener to countrywoman Alberta Brianti in a three setter, losing 6-1, 2-6, 2-6 in one hour and 37 minutes of play.

No.15 Sara Errani, another talented Italian in the draw, got past Indian ace Sania Mirza 6-2, 6-3 in a fine display of power tennis. This is Mirza's fourth consecutive first round feat, following disappointments from Wimbledon, Elkridge and Birmingham.

Other notable first round winners of the day were Kimiko Date-Krumm, Anastasia Rodionova, Ayumi Morita, Barbora Zahlavova-Strycova, Alla Kudryavtseva, Sloane Stephens, Tamira Paszek and Marina Erakovic, who edged 14th seed Elena Vesnina 6-1, 6-2 in just 86 minutes of play.