Men's champion Stan Wawrinka avenged a tough defeat to Kei Nishikori at last year's US Open at the Australian Open on Wednesday.
The quietly confident Wawrinka, who was beaten in the quarter-finals by Nishikori at Flushing Meadows, took his opportunities to produce a surprisingly comfortable victory as he negated the Japanese fifth seed's baseline game.
"I'm still nervous even after the end of the tiebreak," Wawrinka said in a courtside interview of the 6-3, 6-4, 7-6(6) victory that he sealed with his 20th ace on his sixth match point after he had established a 6-1 lead in the tiebreak.
"There is no easy match even from the first round. I am playing well and I'm happy to be back playing the semi-final."
It was the 29-year-old Swiss' first win over a top-five player since he beat Roger Federer in Monte Carlo last year and the workmanlike victory undoubtedly sent a warning to four-times champion Novak Djokovic he would need to be at his best to reclaim the Australian Open title.
Djokovic plays big-hitting Canadian Milos Raonic later on Rod Laver Arena with the winner to meet Wawrinka in the semi-finals.
