Serena Williams vowed to make a swift return to the practice court after crashing out of the Australian Open.
Williams turned in an error-strewn performance in her 6-2 6-3 loss to Ekaterina Makarova to suffer her first defeat in Melbourne since 2008 when she lost to Jelena Jankovic in the quarter-finals.
The American, a 13-time grand slam winner, made 37 unforced errors compared to just 17 from the Russian and admitted afterwards she was determined to get her game back on track.
She said: "I am always thinking about things I can do better next time around. That's usually how I respond.
"I'm already thinking about practising as soon as tomorrow. I can think of 100 things I can do."
Williams has missed the best part of 18 months through injury - she had to sit out last year's Australian Open - and her lack of match practice seemed to catch up with her in the blistering heat.
"I didn't play well and I'm not physically 100%," added the 30-year-old, who was also battling an ankle injury.
"So I can't be so angry at myself, even though I am very unhappy. I know I can play 100 times better than I did this whole tournament."
World number 56 Makarova was delighted to have registered the biggest win of her career.
"I'm surprised because she's a great player and it's really tough to play against her," she said.
"But I was feeling so good and so focused. I played my game and that's it.
"I won against Serena, that's amazing."
It does not get any easier for Makarova as she now faces countrywoman Maria Sharapova, who outlasted Sabine Lisicki in three sets.
Sharapova, who also beat the German in the Wimbledon semi-finals last year, prevailed 3-6 6-2 6-3.
It seemed plain sailing for the fourth seed when she coasted into a 3-0 lead only for Lisicki to hit back to win six games in a row and take the first set.
Sharapova refocused and started to get the better of some hard-hitting baseline rallies as her opponent's belief started to wane.
She levelled it up and then stood firm on the big points to advance in two hours and 15 minutes.
"There were a lot of ups and downs tonight but fortunately I finished on a high note," said Sharapova.
"She's such a good opponent, she has such a big game and even though I didn't play my best tennis tonight I fought until the end and that got me through."
Earlier, Ana Ivanovic's bid to reach her first grand slam quarter-final in three and a half years foundered at the hands of second seed Petra Kvitova.
Ivanovic's impressive run in Melbourne offered hope she could be reclaiming the kind of form which saw her land the 2008 French Open - the last time she advanced to the last eight at a major - and reach the top of the world rankings.
But even though she held her own for much of the contest, especially towards the end of the second set as Kvitova's concentration deserted her, the Wimbledon champion possessed too much power and guile for the Serbian.
"She is a tough opponent," said Ivanovic.
"You really have to try to get a swing on the ball and hope you get some rhythm and that's going to cause some errors. That's what happened to me today.
"But it has been a nice tournament for me, I played some really good tennis and proved to myself that I can play at that level and compete against the best."
Kvitova, who will meet Sara Errani in the quarter-finals after the Italian thrashed Jie Zheng 6-2 6-1, said: "It was a tough match, especially at the end.
"I was happy with how I played in the tie-break."