Pierce was well short of her best against Benesova

The 31-year-old appeared to struggle with her contact lenses, and was always on the back foot.

Benesova chased down a series of seemingly lost causes to overcome Pierce, breaking serve five times.

She will face Martina Hingis in the next round after the former world number one thrashed Emma Laine 6-1 6-1.

Pearce was disappointed with her error-strewn performance, but said she was confident she could return to form.

"I think we all have a bad day sometimes," said Pierce.

"I haven't had a bad match since probably April or May. If I only have a bad match every nine months, it's OK.

"I'm human. It happens."

Meanwhile, Hingis continued to prove her return to competitive tennis after a three-year gap should be taken seriously.

The 25-year-old took 52 minutes to see off her opponent, making just nine unforced errors.

"Maybe I freshened up a little - I'm just really enjoying every second of being around here," said Hingis.

Kim Clijsters reached the third round, but looked well short of being a title contender as her injury problems continued.

The Belgian had been a major doubt with a hip injury before the tournament, and needed treatment during Thursday's match against Yuan Meng.

Clijsters looked unhappy throughout but still had too much for Yuan, winning 6-4 6-2.

She now plays Marion Bartoli or Roberta Vinci, but her fitness must be a doubt.

"I'm happy with the win but my body doesn't feel too good at the moment," Clijsters admitted afterwards.

"I'm happy to get through and give myself another day off tomorrow and hopefully I'll recover better."

France's Amelie Mauresmo held her nerve in a tight opening set before seeing off compatriot Emilie Loit on the Vodafone Arena.

The third seed raised her game as the match went on to secure a 7-6 (7-1) 6-2 victory and a third-round clash with Michaella Krajicek, who upset India's Sania Mirza.

The 17-year-old Dutch player - sister of former Wimbledon champion Richard - beat 32nd seed Mirza 6-3 7-5 to reach the last 32.

Samantha Stosur gave her home crowd plenty to cheer as she beat 21st seed Ana Ivanovic.

The Aussie had strong support from the crowd on Rod Laver Arena and Ivanovic, 18, struggled with her forehand.

Stosur broke in game six on her way to taking the first set and fought back from 4-1 down in the second.

She went on to complete a 6-3 7-5 victory that set up a clash with Sybille Bammer, who beat Zi Yan.