World No.1 Novak Djokovic smashes his racquet in frustration on court during his quarter final match against Germany's Alexander Zverev on Tuesday. Image Credit: Reuters

Eight-time winner Novak Djokovic braved a serious abdominal injury to make his 39th Grand Slam semi-final at the Australian Open, but not before smashing his racket during the demanding four-setter against Germany’s Alexander Zverev.

It was a patchy performance from the world number one, who drew deeply on his mental fortitude to win 6-7 (6/8), 6-2, 6-4, 7-6 (8/6).

Djokovic will be hot favourite to advance to Sunday’s final when he plays Russian qualifier Aslan Karatsev, who continued his dream run with a 2-6, 6-4, 6-1, 6-2 win against injured Bulgarian Grigor Dimitrov.

The Serb remains on track for a record-extending ninth Australian Open title and 18th Grand Slam trophy, nipping at the heels of rivals Roger Federer and Rafael Nadal, who both have 20.

Tennis-Djoko racket abuse
A ball girl sweeps up debris after Djokovic smashed his racket during his quarterfinal as Zverev walks past her at the Australian Open in Melbourne on Tuesday. Image Credit: AP

Zverev lost to Dominic Thiem in last year’s Melbourne semi-finals, and fell agonisingly short against the Austrian at last year’s US Open in his only Grand Slam final.

The implosive nature of the world No.1 Serb has dogged him right through his career, with him paying dearly when he was disqualified from last year’s US Open after hitting a line judge with a ball.

After having lost a crucial point against Spain’s Pablo Carreno, he took a ball out of his pocket, and in a spontaneous show of frustration, hit it behind him without looking, striking the lady line judge in her neck.

“I’m extremely sorry to have caused her such stress. So unintended. So wrong,” Djokovic said. “As for the disqualification, I need to go back within and work on my disappointment and turn this all into a lesson for my growth and evolution as a player and human being,” Djokovic added in a statement on Instagram.

Then again in early January, Djokovic let his frustrations get the better of him at the ATP Cup on Saturday, destroying a racquet in a furious meltdown during a match against Russia’s against Daniil Medvedev in the semi-final.