Ana Ivanovic put paid to the hopes of home favourite Sam Stosur to set up a fourth-round clash with Serena Williams at the Australian Open.
Ivanovic recovered from losing a topsy-turvy first set to win 6-7 (8/10) 6-4 6-2 under the roof on Rod Laver Arena.
Both women wasted chances to take the opener before Stosur finally took it on a tie-break after a brief interruption when the heavens suddenly opened.
But Ivanovic, unbeaten this season after winning a title in Auckland, fought back impressively, smashing 46 winners.
Ivanovic said afterwards: "She's a very tough opponent, she played very well, served well, but I hung in there. They were tough conditions, it was hotter when the roof got closed but I'm so happy and thrilled to be through."
Ivanovic has not won a set in four previous meetings against Williams, three of which have been at the US Open.
She said: "We had really tough matches in the past. In Auckland I played Venus. I didn't have many wins against her and I played a really good match. That gives me confidence for the next match. I look forward to the challenge."
Williams was again relatively untroubled in securing her progress, beating old rival Daniela Hantuchova 6-3 6-3 in intense heat.
It was her 61st win in the singles main draw at the Australian Open, more than any other woman.
Fourth seed Li Na came extremely close to the exit door, saving a match point before battling past Lucie Safarova 1-6 7-6 (7/2) 6-3 in an error-strewn match.
Czech Safarova served for the win at 5-3 in the second set and then held a match point at 6-5 but missed a backhand by a fraction.
Li, who lost in the final to Victoria Azarenka last year, said: "I think the five centimetres saved my tournament. If she hit it in, I think my whole team was on the way to the airport.
"At least I won the match, so I'm still in the tournament. I was really happy the way I fought on the court from the first point until the last point."
Li's countrywoman Zheng Jie was the player to suffer the most on Friday with the heat, which again topped 40c.
Zheng was treated by the doctor after struggling to breathe and feeling dizzy, with the Chinese player lying down on her bench at the side of the court during her clash with Australia's Casey Dellacqua.
She said: "I felt so hot, my brain was not working. Sometimes I watched the ball but I could not focus. My heart was beating fast. I could not take deep breaths."
Wild card Dellacqua ran out a 6-2 6-4 winner, reaching the fourth round for the second time, and first since her comeback from shoulder surgery.
She next meets 19-year-old Eugenie Bouchard, who is through to the fourth round at a grand slam for the first time after a dominant 6-2 6-2 victory over America's Lauren Davis.
Ninth seed Angelique Kerber is also through after a 6-3 6-4 win over America's Alison Riske and next meets Italian Flavia Pennetta, a 6-1 7-5 winner over Mona Barthel.
Russian Ekaterina Makarova, a quarter-finalist the last two years, is one win away from matching that after a 6-4 6-4 victory against Monica Niculescu to set up a meeting with Li.
Third seed Maria Sharapova will hope to have recovered from her epic clash with Karin Knapp when she meets Alize Cornet on Saturday, while Azarenka plays Yvonne Meusburger.