MELBOURNE, Australia — Serena Williams ignored pain and frustration to reach the third round of the Australian Open with a straight sets win over Gisela Dulko on Thursday.

It was far from routine.

The second-seeded Williams, hoping to extend a sequence of winning the Australian title every alternate year since 2003, had to fend off six set points in the ninth game of the second set to prevent the match going to a third. That game went to a dozen deuces before Williams broke to get back on serve.

She got treatment on her left ankle in the changeover and, grimacing with pain, held and then broke Dulko again — this game going to deuce a half-dozen times — to get her chance to serve it out.

After all that, the nine-time Grand Slam winner finished with ace on her first match point, advancing in 1 hour, 50 minutes.

"It was a very tough second set, she started playing unbelievable, hitting winners left and right," Williams said. "She had a couple of opportunities but I always felt I wasn't going to lose.

"I feel I could play a lot better."

Williams converted only four of her 18 break chances against the 23-year-old Argentine. Dulko was successful on both of hers.

Olympic champion Elena Dementieva improved her 2009 winning streak to 12 matches with 6-4, 6-1 win over Iveta Benesova.

Dementieva, who won titles at Auckland and Sydney before the season's first major, struggled with her serve early but recovered to finish the match in 72 minutes.

The 27-year-old Dementieva reached the French Open and U.S. Open finals in 2004, beaten both times by fellow Russians, and has not returned to the championship of a Grand Slam tournament since.

Her highlight last year was a win over fellow Russian Dinara Safina in the gold medal match at the Beijing Olympics. She was ousted in the semifinals at Wimbledon and the U.S. Open in 2008 and has never advanced beyond the fourth round at Melbourne Park.

Amelie Mauresmo, who won here and at Wimbledon in 2006, rallied for a 4-6, 6-3, 6-2 win over Britain's Elena Baltacha. Mauresmo, a former No. 1 now seeded 20th after an injury-plagued 2008, advanced when Baltacha double-faulted on match point.

Fellow Frenchwoman Virginie Razzano ousted No. 14 Patty Schnyder of Switzerland 6-3, 6-1.

Other women advancing included No. 13 Victoria Azarenka of Belarus and No. 18 Dominika Cibulkova of Slovakia, a 6-0, 6-2 winner over Taiwan's Chan Yung-jan.

Men's No. 1 Rafael Nadal takes on Roko Karanusic and No. 4 Andy Murray has the last night match on the Rod Laver Arena.

No. 6 Gilles Simon of France won the opening match on center court at Melbourne Park, beating Australian Chris Guccione 6-7 (5), 6-4, 6-1, 6-2.

For the first time in six years, Amer Delic is still in contention after two rounds.

And to think, he thought he was heading home after he lost 6-0, 6-7 (3), 6-0 to Florian Mayer in his third qualifying match.

The 26-year-old Bosnian-born American got a place in the main draw as a lucky loser and knocked off No. 28-seeded Paul-Henri Mathieu in the second round in five sets Wednesday. His next assignment will be tougher: defending champion Novak Djokovic.

"Things have been going my way," he said. "Why stop it here?"

Given the history in the Balkans, and the mix of its migrants to Australia, the atmosphere for Delic's match against the 21-year-old Serb will have an edge to it.

Delic's run has attracted a group of enthusiastic fans — unruly according to the father of his vanquished first-round rival, fellow American Taylor Dent; disrespectful by Mathieu's reckoning.

The flag-waving Bosnians who are following Delic traded chants across the court with Serbian fans Wednesday, during, before and after points against his French rival.

"I couldn't control any of that, though I was trying to," Delic said. "I felt bad for Paul and I apologized to him right after."

Any extra tension for Friday's match is what police, local organizers and Delic want to avoid.

He said his family moved to Florida in 1996 to get away from any conflict, his parents wanting to start a new life after the Bosnian war.

"I just hope the next match with Novak doesn't turn into a World War III," he said. "I'm going to try to tell my fans that we don't need to be embarrassing ourselves in front of the world. I'm hoping Novak says something to Serbian fans, also. Leave the politics aside.

"It's not my fault and it's not Novak's fault. We're out here playing tennis and we need to keep it that way."