Novak Djokovic lost his temper but refused to let the prospect of Australian Open glory slip away as he edged out Alexander Zverev to reach the semi-finals.
The world number one destroyed a racket when trailing 3-1 in the third set, after he and Zverev split the opening two sets, and it was one of a number of moments when the Serbian showed heightened volatility during a 6-7 (6-8) 6-2 6-4 7-6 (8-6) win.
Still bothered by an abdominal problem that he sustained in the third round, Djokovic nevertheless strides on and will face Russian qualifier Aslan Karatsev for a place in the final.
Zverev, who played in a bright yellow headband and vest top, with a gold medallion hanging from his neck, will look back on an opportunity missed.
As well as that third-set lead, Zverev was also up a break at the start of the fourth, but the US Open runner-up lacked the composure to convert those hard-earned positions.
If Djokovic's racket-smashing was a tactical move designed to gee himself up and distract Zverev, then it worked a treat.
A nip-and-tuck opener had gone the way of German world number seven Zverev, who then made a wretched start to the second set and was 4-0 behind in the blink of an eye.
Just as momentum began to swing back Zverev's way in the third, Djokovic went into his rage, with a ball girl summoned to clear up the mess the 33-year-old created.
Back came Djokovic as double faults began to leak from Zverev's racket, and soon they were into a fourth set.
Zverev led 3-0 but Djokovic was not going away, seizing on mistakes from an opponent who by the end of the second tie-break of the match could only wonder what might have been.
An ace from Djokovic finished off the contest. After eight titles at Melbourne Park, a hunger for more continues to define his every performance in Australia.
"Emotionally I feel a little bit drained. We pushed each other to the limit," Djokovic said in his on-court interview.
"Other than in the second set I started pretty poorly in all the other three sets. I lost my service very early in the first, third and fourth and allowed him to swing through the ball a bit more, but I regained my focus.
"I broke that racket and things started to shift a little bit for me in a positive direction."