Pennetta books Li date

Italian Flavia Pennetta caused a minor shock when she ousted ninth seed Angelique Kerber 6-1 4-6 7-5 in Melbourne.

The 31-year-old set up a quarter-final clash with Li Na with a hard-fought victory over the German in an hour and 52 minutes.

Pennetta, who reached the semi-finals of the US Open last year, was dropping her first set of the week as her fine form continued.

After being blitzed in the first set in just 24 minutes, Kerbe finally got a break to boost her confidence on Pennetta's opening service game of the second set.

But the Italian's booming forehands were unstoppable and she broke straight back.

Kerber dug deep to save two break points in a crucial fourth game to stay alive at 2-2, and clawed her way back with another break in the next when Pennetta's backhand hit the net.

Kerber then lost her serve again before she pounced with another break in the ninth game, drilling a forehand down the line to get on top at 5-4 and she served out for the set.

She had to save two break points at the start of the decider and the pair did exchange breaks before Pennetta forced a backhand error to move ahead 5-3, and although nerves got the better of her as she failed to serve it out the 28th seed came right back to break again to seal the win.

"I missed last year so it is good to be back and I'm shaking," she said, referring to a serious wrist injury that kept her out of last year's tournament.

"I'm a bit older now and starting to enjoy just playing tennis more and everything is good so far... The first set was one of the best I have ever played."

Fourth seed Li Na will make a formidable quarter-final opponent after she thrashed Ekaterina Makarova 6-2 6-0 in just 59 minutes.

The two-time finalist broke the Russian five times and brushed off break points against her to move 5-2 ahead in the opening set.

Again Makarova had break points in the fourth game of the final set but Li was not to be denied as she booked her date with Pennetta.

"At least she's one day older than me, so I'll play an older player," Li said of the Italian, both turning 32 next month. "So nobody will talk about my age."