A resurgent Roger Federer weathered a belated challenge from Andy Murray at the Australian Open to win 6-3, 6-4, 6-7, 6-3 and set up a mouthwatering semi-final with rival Rafa Nadal.
Stingy on serve and dominant at the net, the 17-times grand slam champion wobbled when serving out for the match at 5-4 in the third set and was dragged into a tiebreak in an atmosphere of unrelenting tension at Rod Laver Arena.
Battling fatigue, Murray saved two match-points to keep his bid for a third grand slam title alive but met ever stiffer resistance from the imperious Swiss who attacked his serve with abandon in the final set.
Having saved a raft of break points, the 26-year-old crumbled at 4-3 to concede the decisive break and Federer made no mistake on his third match point, sealing the thriller with an ace after three hours and 20 minutes.
On the women's side, silent assassin Agnieszka Radwanska toppled a shrieking two-time defending champion Victoria Azarenka 6-1, 5-7, 6-0 and reach her maiden Australian Open semi-final.
The crafty Pole frustrated Azarenka with a scrambling, cat-and-mouse game early and completely dismantled the Belarusian in the final set to close out one of her finest victories in two sun-drenched hours at Rod Laver Arena.
In a tournament littered with big upsets, Radwanska booked a semi-final against 20th seed Dominika Cibulkova, and put herself in the box seat to crack her first grand slam title after coming close in a heartbreaking loss to Serena Williams at Wimbledon in 2012.
Radwanska also missed a big chance at the championships last year when she was dumped by unheralded German Sabine Lisicki in the semi-finals.