MELBOURNE (AFP) - Favourite Serena Williams complained she was "rusty" heading into the Australian Open fourth round Saturday but it was Russia's Elena Dementieva, seeded four, who squeaked through to the last 16. Dementieva went down 5-2 as a parochial hometown crowd cheered on Australian Samantha Stosur, clawing her way to a 7-6 (8/6), 6-4 third round win when her opponent's errors let her off the hook. Elsewhere, a new generation of talent continued to emerge as teenager Victoria Azarenka of Belarus ousted former champion Amelie Mauresmo and Venus Williams' second round conqueror Carla Suarez Navarro posted an easy win. Three-time Australian champion Serena admitted her sister's shock exit had given her extra motivation in the tournament and brushed aside China's Peng Shuai 6-1, 6-4 to book a fourth round meeting with Azarenka. Well-known for only hitting her peak in the second week of a Grand Slam, she did not seem overly concerned at a patchy period against Peng early in the second set. "I'm feeling a little rusty for whatever reason. I'm hoping my next round I'll be a little better," she said. She was relishing the prospect of meeting Azarenka, 19, whom the American bounced from the tournament last year but who has gone on to become a rising star and collect her maiden tour title earlier this month. "Obviously she's young and desperate to win and hungry, all the qualities that it takes to be pretty good," Williams said, seeded two this year. The American remains on track for a potential semi-final showdown with Dementieva and will be rubbing her hands in anticipation if Russia's Olympic gold medallist displays the big-match fragility on show against Stosur. Despite her high ranking, the talented 27-year-old has underachieved at Grand Slams for a decade and was overwhelmed early in the match as a roaring Melbourne Park crowd urged on Stosur. "I was nervous to play against her here," she said. "I'm sure she feels very comfortable, you know, playing on this court with the crowd support, it wasn't easy for me." However, Dementieva took heart from a fightback that took her winning streak this year to 13 matches. It was a case of the new guard pushing aside the old when Azarenka beat former world number one and 2006 Australian champion Mauresmo 6-4, 6-2. The Frenchwoman showed glimpses of the form that earned her two Grand Slams but could not withstand the challenge from a player 10 years her junior. Another young gun Carla Suarez Navarro of Spain backed up her shock second round win over Venus Williams to beat countrywoman Maria Jose Martinez Sanchez 6-1, 6-4. The 20-year-old is playing in her first Australian Open and now has a good chance of progressing to the quarter-finals, equalling her best Grand Slam result at the 2008 French Open. Eighth seeded Russian Svetlana Kuznetsova also advanced when she downed Ukraine's Alona Bondarenko 7-6 (7/5), 6-4, while Chinese 22nd seed Zheng Jie beat Bonderenko's sister Kateryna Bondarenko 6-2, 6-2. Spanish 21st seed Anabel Medina Garrigues completed the fourth round line up in the bottom half of the women's draw with a 6-4, 6-1 win over Italian 12th seed Flavia Pennetta.