Eighth seed Venus Williams reached the last eight at the Australian Open with a hard-fought win over Poland's Marta Domachowska on Monday.
The American twice came back from a break down in the first set on her way to a 6-4 6-4 victory.
Williams will play fourth seed Ana Ivanovic in the last eight after the Serb overcame a tough examination by Denmark's Caroline Wozniacki.
Ivanovic battled to a 6-1 7-6 (7-2) win over the unseeded 17-year-old.
Wozniacki, a former Wimbledon junior champion, put up a strong fight and served to level at one set all.
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Serbia's Ivanovic had to save three break points in the first set and a set point in the second before clinching a place in her first Australian Open quarter-final.
"She had nothing to lose, so she was really dangerous in the second set," said Ivanovic.
"I started fighting a little bit more and I'm really happy I managed to keep my composure in the end of that second set and be calm on those set points and still manage to win it."
Poland's Agnieszka Radwanska, the 29th seed, staged a dramatic fightback to beat 14th seed Nadia Petrova of Russia 1-6 7-5 6-0.
"I was losing 6-1, 3-0 and I was thinking, 'what am I doing wrong?'," said Radwanska. "It was so quick and she was using the wind very well, and I wasn't.
"It was hard to see a way out of it but I just kept fighting for every point "
"I think that was the most important point in this match. Then I started to play, try to do something else. It was very long games and I won the second set. It was so close."
She will next play ninth seed Daniela Hantuchova, who came back from a set and 3-1 down to beat Maria Kirilenko 1-6 6-4 6-4.
"It was hard to see a way out of it but I just kept fighting for every point and tried to change my game a little bit," she said.
"I went for my shots and thought I played pretty well."
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