MELBOURNE: Roger Federer and Serena Williams showed championship form to battle back from a set down and storm into their semi-finals at the Australian Open on Wednesday.
Li Na also made the last four with an upset victory over Venus Williams, giving China two players in a Grand Slam semi for the first time.
She will play defending champion Serena for a place in the final.
Top seed Federer was dealt a scare in his quarter-final by sixth seed Nikolay Davydenko when the Russian ace led 6-2, 3-1 before the Swiss star clicked into gear.
He won 13 straight games to take the next two sets before a titanic struggle in the fourth with the 15-time Grand Slam champion eventually coming home 2-6, 6-3, 6-0, 7-5 to end Davydenko’s 13-match winning streak.
It puts Federer into his 23rd consecutive Grand Slam semi-final, having never missed out since his third round defeat to Brazilian Gustavo Kuerten at Roland Garros in 2004.
He next plays either third seeded Serbian Novak Djokovic or French 10th seed Jo-Wilfried Tsonga.
“I’ve played him many times and I know he goes through phases for half an hour, an hour,” Federer said of Davydenko.
“You’ve just got to stick with him and if you don’t he’s going to crush you.
“All of a sudden I went on a run like I did and that was a bit surprising, but I needed that cushion at the end of the fourth when he played well.”
Asked if he was concerned that he might lose, he said: “I was a touch worried, let’s put it that way.”
Fifth seeded Andy Murray faces 14th seed Marin Cilic in the other semi-final, with the Scot seeking to win Britain’s first Grand Slam title since Fred Perry in 1936.
Like Federer, Serena was also on the ropes before staging a stunning comeback to stay on track for her 12th Grand Slam title and fifth in Australia.
She was down 4-6, 0-4 to seventh seed Victoria Azarenka before fighting back and winning a tense tiebreaker to level the match.
Azarenka was rattled and Serena rammed home her advantage in the final set to win 4-6, 7-6 (7/4), 6-2 and set up a clash with Li, who came from behind to shock Venus 2-6, 7-6 (7/4), 7-5.
Justine Henin and unseeded Chinese Zheng Jie will contest the other semi.
“I am surprised and I am just happy to still be here,” said Serena. “I didn’t expect to win when I was down 0-4.
“I was like ‘well at least I am still in the doubles’.
“I was thinking if I lost today and lost the doubles I could get a flight home on Friday.”
Venus should have made it a sister act in the semis, but she threw it away against Li in a scrappy match where they made a incredible combined 110 unforced errors.
She was a set and 4-2 up in the second when Li made her move, becoming more relaxed as she began to play with greater freedom.
At the same time, Venus tightened up as her forehand went to pieces.
Venus, who has won seven Grand Slam titles but never been at her best in Melbourne making only one final in 11 attempts, admitted Li was the better player.
“I think I was playing good tennis – I don’t think it has anything to do with whether I was playing good,” she said.
“I have to give her a lot of credit for playing well and picking her game up.”
Making the semi-finals of a Grand Slam for the first time was a dream come true for the Chinese 16th seed.
“It’s the best day of my whole life,” an exuberant Li said.
“It’s good for both players and it’s good for Chinese tennis.”