No. 3 ranked Vera Zvonareva of Russia converted the only two service breaks of the match, enabling her to beat qualifier Jill Craybas 6-4, 7-5 Tuesday night in the Mercury Insurance Open.

The top-seeded Zvonareva, playing her opening match, had more trouble than expected against the American. Craybas won two qualifying matches to get into the main draw, then won her first-round match on Monday.

"She got a couple of matches under her belt and got used to the conditions so I knew it was going to be a tough one," Zvonareva said. "I don't expect myself to play my best tennis in the first match of the tournament."

The pair were on serve in the first set when Zvonareva had the only service break of the set in the ninth game to take a 5-4 lead. Craybas, ranked No. 125, wasted two break points in the next game before dropping the set with a backhand into the net.

Zvonareva broke Craybas' serve in the 11th game of the second set to take a 6-5 lead before serving out for the win.

"That was very good that I was able to convert those break points and I was able to play some good tennis when I needed it," Zvonareva said. "I fought very hard and played some good points when I needed them."

No. 2 seed Andrea Petkovic of Germany also had her first action of the tournament and defeated Alexa Glatch of the United States 6-3, 6-4.

Third-seeded Agnieszka Radwanska of Poland was extended before winning her opening match with a 6-0, 7-6 (4) win over Great Britain's Elena Baltacha.

Radwanska, who received a bye into the second round, saved two set points at 5-4 in the second set before Baltacha saved one match point to force the tiebreaker.

Three seeded players lost as qualifier Marina Erakovic of New Zealand upset No. 14 seed Elena Vesnina of Russia 6-1, 6-2, Alberta Brianti of Italy was a 1-6, 6-2, 6-2 winner over 10th-seeded Flavia Pennetta of Italy, and No. 13 seed Jarmila Gajdosova of Australia lost to Russia's Alla Kudryavtseva 6-3, 6-2.

No. 11 seed Maria Kirilenko of Russia cruised to a 6-3, 6-2 win over Canada's Rebecca Marino; 12th-seeded Sabine Lisicki of Germany beat Italian Greta Arn 6-0, 6-2; and No. 15 seed Sara Errani of Italy defeated Sania Mirza of India 6-2, 6-3.

Radwanska, runner-up in the finals here last year to Svetlana Kuznetsova, was in quite a struggle after an easy first set.

"I was serving very aggressively really playing my game," Radwanska said. "She was serving much better in the second set and it was hard to break her."

Kirilenko did not face a break point on her serve as she hit 75 percent of her first serves. She also took advantage of a back injury Marino suffered in the first set.

Kirilenko, who lost to eventual champion Serena Williams in the quarterfinals last week at Stanford, was rarely pushed by her Canadian opponent.

"I think I played great today," Kirilenko said. "I did everything that we planned. I was happy with that. I tried to mix my game because she is tall."

Both players sought injury treatment at the end of the first set. The Russian saw a trainer or a pain in her left leg, Marino for a lower back injury.

"I did a couple of drop shots and I could see that she was running a little bit (slower)," Kirilenko said.

Lisicki, who lost to Maria Sharapova in the Wimbledon semifinals, was pleased with her overall game.

"I didn't have too much time to adapt because I just came here two days ago," she said. "A little bit different conditions (than last week at Stanford), so I was happy with the way I played."