MELBOURNE, Australia - The underdogs continued to rise up on a hot and muggy Monday Down Under, as Ekaterina Makarova and Sara Errani - both unseeded - got into the final eight with surprisingly routine straight set victories.

Makarova made the biggest headlines of the day, and perhaps the whole tournament, stunning five-time Australian Open champion Serena Williams, 62 63. Williams, who had rolled her ankle at the lead-up event in Brisbane and wasn't really moving her best in her first three rounds, made 37 errors to just 24 winners, even her big serve not coming through - nine aces but seven doubles.

Meanwhile the 56th-ranked Makarova was on her game, dropping the first two games of the second set but otherwise dominating Williams with pinpoint lefty serves and groundstrokes - her down-the-lines were especially effective.

"I'm surprised because she's a great player and it's really tough to play her. But I was feeling so good and so focused," Makarova said afterwards. "I played my game and that's it, I won against Serena Williams. That's amazing."

In the pair's only previous meeting, Williams won easily in Beijing in 2009. "When I played her in Beijing I was really afraid of her," Makarova added. "But this time I felt so comfortable. I really thought I could beat her today."

Makarova was also asked about her last name, which has been likened to a certain pop song from the '90s. "Sometimes when I'm playing, the crowd, they start saying Macarena or Macaroni. I don't like it really," she said with a smile. "I really like Italian food, of course, I just don't like how they call me that. In Russia it's a really popular family name. But that's okay. I'm used to it."

"I think she played very well," Williams commented, "she went for broke on a lot of her shots and I made 37 errors. That kind of tells the story of the match.

"It was definitely hot out there. I guess I just didn't move the way I wanted to. And I can't even describe how I served. It wasn't good, though. My lefty serve is actually better than that. Maybe I should have started serving lefty.

"It was just disastrous really.

"But she played really well and deserved to win today. I look forward to our next match. I feel like I can definitely play so much better. And that's good - like if I felt like I couldn't play better, then that would really be a problem."

Further on the subject of her recent injury, Williams was asked whether she would have played in Melbourne if it weren't a Grand Slam. "No, no way," the 13-time Slam winner said. "I probably shouldn't have played. But no way."

Williams had been 18-0 against lefties at Grand Slams going into the match.

Another unseeded player joining Makarova in the last eight was the 48th-ranked Errani, who beat two-time Grand Slam semifinalist and former Top 15 player Zheng Jie routinely, 62 61. Errani's heavy topspin was too much for Zheng, who had also lost their only previous meeting by a similarly easy score: 61 62.

"It's incredible for me," Errani said of her run. "I think I have a game that is difficult for Zheng Jie. If I play high balls, she has to go back and maybe that's more difficult. It was very hot today too, so it was difficult for both of us."

Unlike Makarova and Errani, the day's other winner won't be playing their first Grand Slam quarterfinal at all. No.2 seed Petra Kvitova reached fourth Slam quarterfinal with a 62 76(2) win over No.21 seed Ana Ivanovic. Kvitova lost her serve at love while serving for the match earlier in the second set, but the potential soon-to-be No.1 regrouped in time to close out the former No.1.

"I'm lucky I'm not playing a third set," Kvitova said afterwards. "I'm happy I won the second set because in the end it was very tough to come back."

"It was a real pity I didn't use the opportunities I had, but she served so well," Ivanovic said. "I tried really hard today. My rhythm was lacking a bit."

Kvitova and Errani will play in the quarterfinals, a first-time meeting.