Unseeded Cypriot Marcos Baghdatis extended his extraordinary run at the Australian Open, upsetting seventh seed Ivan Ljubicic of Croatia 6-4 6-2 4-6 3-6 6-3 to reach the semi-finals.
Baghdatis, a former world junior number one currently ranked 54th, followed his shock win over second seed Andy Roddick with another gritty victory under floodlights at the Rod Laver Arena.
Baghdatis played superbly in the first two sets, unleashing his full range of shots to grab a two-set lead before Ljubicic fought back to win the next two and force the match into a decider.
Baghdatis, 20, fended off two break points in a tense third game then ripped a cross-court forehand past Ljubicic to gain the decisive break in the next game.
He coolly held his remaining three service games to advance to Thursday's semi-final against Argentine fourth seed David Nalbandian, who beat unseeded Frenchman Fabrice Santoro 7-5 6-0 6-0 earlier in the day.
Nalbandian mastered unseeded Santoro's unorthodox game and charged into Thursday's semis with a lopsided 7-5, 6-0, 6-0 victory in just 1hour 41minutes on the Rod Laver Arena.
Nalbandian, the conqueror of world number one Roger Federer in the Masters Cup final in Shanghai last November, is closing in on his second slam final after losing to Lleyton Hewitt in 2002 at Wimbledon.
Once he worked out a way to adapt to Santoro's distinctive touch play around the net, he surged to victory, carrying off the last two sets without losing a game.
Santoro frustrated him and got a service break in the seventh game of the first set when Nalbandian netted a forehand, but the Argentine broke straight back in the next.
Nalbandian held two break points and broke again for the opening set with a forehand winner down the line off a short return from the Frenchman.
It was all plain sailing from there with three service breaks to race away with the second set to love.
Santoro posed no problems for Nalbandian as his game fell away and confidence drained and he was again broken three times in the final set.
Australian Open men's singles quarter-final results
Marcos Baghdatis (Cyp) bt I Ljubicic (Cro)(7) 6-4 6-2 4-6 3-6 6-3
David Nalbandian (Arg)(4) bt Fabrice Santoro (Fra) 7-5 6-0 6-0
