Serena Williams ignored pain and frustration to reach the third round of the Australian Open with a straight-sets win over Gisela Dulko today.

The second-seeded Williams' 6-3, 7-5 win was far from routine, unlike Rafael Nadal's 6-2, 6-3, 6-2 win over Croatia's Roko Karanusic to progress to the third round.

China's Zheng Jie, seeded 22nd, defeated Melinda Czink of Hungary 7-6 (0), 5-7, 5-3.

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 latched on to both of hers.

Nadal was more emphatic against Karanusic, fending off six break points the bearded Croat had against his serve and converting on six of the seven chances he had.

The 22-year-old Spaniard will next play German veteran Tommy Haas, who beat Flavio Cipolla, Italy, 6-1, 6-2, 6-1.

No. 6 Gilles Simon advanced, along with No. 13 Fernando Gonzalez of Chile, the 2007 runner-up, beat Argentina's Guillermo Canas 7-5, 6-3, 6-4.

No. 17 Nicolas Almagro, No. 24 Richard Gasquet and No. 31 Jurgen Melzer also went through. Dudi Sela was the first Israeli man to make the third round of a major since 1994.

On the women's side, Olympic champion Elena Dementieva improved her 2009 winning streak to 12 matches with 6-4, 6-1 win over Iveta Benesova.

Dementieva struggled with her serve early but recovered to finish the match in 72 minutes.

The 27-year-old Dementieva reached the French Open and US 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 US 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 removed No. 14 Patty Schnyder of Switzerland 6-3, 6-1.

Other women advancing included No. 12 Flavia Pennetta of Italy, No. 13 Victoria Azarenka of Belarus, No. 18 Dominika Cibulkova of Slovakia and No. 21 Anabel Medina Garrigues of Spain.

(Agencies via Shanghai Daily January 22, 2009)