According to Novak Djokovic, he is playing his best tennis in a “long time”, and the Serb got rated as 8 out of 10 by one of the sons of Lionel Messi -- another athlete who has been nearly perfect his entire career.

A victory at Miami would be a landmark 100th singles title for the 24-time Grand Slam champion.

A tennis union co-founded by Novak Djokovic on Tuesday announced a series of legal actions aimed at the sport's governing bodies, alleging "anticompetitive restraints and abusive practices".

Five-time champion Novak Djokovic crashed out in his Indian Wells ATP Masters opener on Saturday, just the latest proof that "things are different" now for the 24-time Grand Slam champion.

The 24-time Grand Slam winner, who retired from his last four match at Melbourne Park in January due to the injury and lost his opener at the Qatar Open last month, also said he was reaping the rewards of his work with coach Andy Murray.

World number one Sinner agreed to a three-month ban on Saturday, admitting "partial responsibility" for mistakes by his team which led to him twice testing positive for traces of clostebol in March last year.

Djokovic's bid for a record-breaking 25th Grand Slam title at the Australian Open was ended when he was forced to retire injured after dropping the opening set against Alexander Zverev in the semi-finals.

The former world number one responded on Saturday, posting a photo of an MRI taken of his left hamstring on the social media platform X with the caption: "Thought I'd leave this here for all the sports injury 'experts' out there."

Djokovic enlisted five-time Melbourne Park finalist Murray to help his quest for a 25th Grand Slam title.

Djokovic's long wait for a record 25th major title will go on, a year after he exited Melbourne Park with a semi-final loss to Sinner.

The irrepressible 37-year-old put to bed any doubts about his ability to add to his 24 Grand Slam titles with a scintillating four-set takedown of Carlos Alcaraz in the Melbourne last eight on Tuesday.

The 10-time Melbourne Park winner Djokovic outlasted the younger Spaniard 4-6, 6-4, 6-3, 6-4 to set up a semi-final with Alexander Zverev.

Ageless Novak Djokovic won an epic generational clash against Carlos Alcaraz on Tuesday to stay on track for an 11th Australian Open title with Alexander Zverev next in the semifinals.

Djokovic, speaking at a news conference in Melbourne where he is taking part in the Australian Open, said that he cannot "pretend that nothing is happening".

"Couple days ago the famous sports journalist who works for official broadcaster Channel Nine here in Australia made a mockery of Serbian fans and also made insulting and offensive comments towards me," he said, not naming him but appearing to reference Tony Jones.

The 37-year-old Serb, who is gunning for a record 25th Grand Slam title and 11th Melbourne crown, beat 24th seed Jiri Lehecka 6-3, 6-4, 7-6 (7/4) on Rod Laver Arena.

A fired-up Novak Djokovic powered into the last 16 of the Australian Open on Friday in an ominous reminder of why he is a 10-time Melbourne champion, but he needed a medical break and used an inhaler.

On-court coaching, previously banned and punishable by point deductions, disqualification or even suspension from tournaments is being positively encouraged at Melbourne Park with "coaching pods" at court level in the corners of the main stadiums.

Novak Djokovic made a slice of Grand Slam history on his way into the Australian Open third round on Wednesday but last year's women's finalist Zheng Qinwen was knocked out in the biggest shock so far.

Former world number one Novak Djokovic's Australian Open preparations suffered a blow Friday as he was bundled out of the Brisbane International by towering American Reilly Opelka.