S.Williams upsets No. 5 seed at Australia

MELBOURNE, Jan. 19 (UPI) -- Unseeded Serena Williams defeated fifth-seeded Nadia Petrova Friday and advanced to the fourth round of the Australian Open.

Williams fell to No. 81 in the world because of injuries and a lack of play. She dropped the first set to Petrova and committed 39 unforced errors before putting together the 1-6, 7-5, 6-3 win. Williams won the event in 2003 and 2005.

She moved into a match against 11th-seeded Jelena Jankovic, who improved to 12-1 on the season with a 6-3, 6-4 brush off of Victoria Azarenka on Friday.

No. 2-seeded Amelie Mauresmo, the 2006 Australian Open champ, also won Friday but was much more convincing, dispatching Eva Birnerova 6-3, 6-1. Her fourth-round opponent will be Lucie Safarova, who advanced when Anastasiya Yakimova retired.

Third-seeded Svetlana Kuznetsova was also impressive in a 6-1, 6-4 rout of Maria Kirilenko, which earned her a fourth-round match with 16-seeded Shahar Peer, a 3-6, 7-5, 7-5 winner Friday over 20th-seeded Tatiana Golovin.

Also, No. 7 Elena Dementieva was a 6-1, 6-3 victor over Maria Elena Camerin and meets 10th-seeded Nicole Vaidisova, who stopped No. 21 Katrina Srebotnik 6-4, 6-4, in the next round.