MELBOURNE, Australia (AP) - Back on the court where he won his only Grand Slam title, Novak Djokovic overcame an early struggle against a journeyman Swiss player before advancing to the third round of the Australian Open.
The third-ranked Djokovic had nine double-faults and 52 unforced errors in his 3-6, 6-1, 6-1, 6-3 win Thursday over Marco Chiudinelli, the Swiss player who was playing in his first Australian Open.
"I was well aware of his quality, and he played extremely well, especially in the first set and the start of the second," Djokovic said. "I was very lucky to get two sets to one up."
"This court is most special because I won my only Grand Slam here," the 22-year-old Serb said of Rod Laver Arena, where he beat Federer in the semifinals en route to the 2008 title. "It has the nicest possible memories."
Djokovic will next play Uzbekistan's Denis Istomin, who beat Michael Berrer of Germany 7-5, 6-3, 6-4.
Sixth-seeded Nikolay Davydenko, who rarely gets onto the center court at this stage of a Grand Slam, had a 6-3, 6-3, 6-0 win over Ukraine qualifier Illya Marchenko in the low-key manner which has typified an 11-match winning streak.
The 28-year-old Russian doesn't have the profile of Roger Federer or Rafael Nadal, and he's never made a Grand Slam final, but nobody has been playing better lately.
He dominated Marchenko on Show Court 2, which is No. 4 in the pecking order of courts at Melbourne Park, to extend a winning sequence that has included title runs at the World Tour Finals at the end of 2009 and Doha to start this year.
Former No. 1-ranked Ana Ivanovic has the profile, but no recent form to go with it. The 22-year-old Serb extended her run of poor results in a second-round 6-7 (6), 7-5, 6-4 loss to Gisela Dulko of Argentina.
Dulko was broken twice while serving for the match before finally breaking Ivanovic's serve - helped by two double-faults from the 2008 French Open champion - to clinch a place in the third round on her sixth match point.
Ivanovic, who lost the 2008 final here, has slipped to No. 21 in the rankings and didn't win a tournament in 2009. It was her first loss to Dulko in their three meetings.
"It's hard. It hurts, I must say. For sure it will. But it's a process," Ivanovic said of her hopes to regain a top-10 position. "I do feel better on the court. I'm playing much better. I feel like my old self. There are still some areas that are not there for me to rely on.
"I just have to sort of keep my head up and try to improve, work."
U.S. Open finalist Caroline Wozniacki of Denmark advanced 6-3, 6-1 over Julia Goerges of Germany and will next play No. 29 Shahar Peer of Israel, who beat Tsvetana Pironkova of Bulgaria 6-1, 6-4.
Among the women advancing were No. 7 Victoria Azarenka of Belarus, No. 9 Vera Zvonareva of Russia, No. 10 Agnieszka Radwanska, No. 16 Li Na of China and No. 32 Carla Suarez Navarro of Spain.
On the men's side, 2006 finalist Marcos Baghdatis struggled late with cramping but held on to beat No. 17 David Ferrer of Spain 4-6, 3-6, 7-6 (4), 6-3, 6-1.
Colombia's Alejandro Falla had a 6-4, 6-1, 6-3 win over Marcel Granollers and will play another Spaniard in the next round - No. 26 Nicolas Almagro beat Germany's Benjamin Becker 6-4, 6-2, 3-6, 4-6, 6-3.
Davydenko beat both top-ranked Federer and No. 2 Nadal on his way to two titles in the last two months, including the Qatar Open this month where he saved two match points in a comeback win over Nadal in the final.
His best run at the Australian Open ended in a fourth-round loss in 2008. He did not play here last year due to a left heel injury, breaking a streak of 29 straight Grand Slam tournaments back to the 2001 U.S. Open.
If players progress according to their seedings, Davydenko would meet 15-time Grand Slam singles champion Federer in the quarterfinals here.
Only seven matches into her comeback, Justine Henin held off fifth-ranked Elena Dementieva 7-5, 7-6 (6), winning the last three points of the tiebreaker to clinch a second-round victory worthy of a final on Wednesday night. She ended it on her second match point - 24 minutes after she missed her first chance against the Olympic champion.
Henin, who retired in May 2008 while she was ranked No. 1, knows she's capable of reproducing the form that took her to seven major singles titles.
"I lived so much emotion on the court this evening. It was magical," she said. "I was afraid I wouldn't be able to do it, but it was the kind of situation I needed to re-find my confidence."
On the men's side, Juan Martin del Potro, the 21-year-old Argentine who upset Roger Federer to win last year's U.S. Open, held off James Blake 6-4, 6-7 (3), 5-7, 6-3, 10-8, while defending champion Nadal and No. 5 Andy Murray each won in straight sets.
Former No. 1 Andy Roddick finished his 6-3, 6-4, 6-4 win over Brazilian Thomaz Bellucci with an expletive-laden rant against Irish chair umpire Fergus Murphy over an interpretation of the rules. He later apologized in a news conference, and via Twitter.
Defending women's champion Serena Williams, playing her first major since she was fined $82,500 for a profanity-laced tirade against a line judge during her U.S. Open semifinal loss to Clijsters, was to play Petra Kvitova of the Czech Republic on Thursday.