MELBOURNE: The Australian Open ended in the early hours of Monday morning with one of the all-time great men's finals.

Here, AFP Sport highlights five talking points from a tournament that began in chaotic fashion and finished with history being made.

No Djok was no joke

The world number one's absence in the most extraordinary circumstances -- detained, visa cancelled and deported on the eve of the tournament -- threatened to drain the life out of the Melbourne Park fortnight before it had even begun.

There was little joy about the "Happy Slam" as the first serve was struck on January 17, with its nine-time champion in a Dubai airport on his way back to Serbia.

The lack of clarity over vaccine rules and exemptions -- exposed through two court hearings and the sight of one of the world's top athletes being incarcerated in a notorious immigration hotel -- was derided as both sad and farcical.

No one emerged with any credit.

Organisers and the Australian government owe a duty to everyone to ensure such controversy never happens again.

T-shirt U-turn

Fans with banners and T-shirts in support of Chinese player Peng Shuai went largely unnoticed until Tennis Australia, the tournament organisers, saw fit to ban the slogan as a "political statement".

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Cue a viral video of human rights campaigners being asked to remove T-shirts by security staff, which turned into a global news story with the likes of tennis legend Martina Navratilova branding the organisers "pathetic".

A hasty Tennis Australia climbdown followed the next day and the supporters handed out more T-shirts before the women's final, ensuring the plight of Peng was kept in the spotlight.

Men behaving badly

Nick Kyrgios has always been a Marmite (or Vegemite if you're Down Under) character. You either love him or hate him.

But his behaviour in the past fortnight on the way to his first Grand Slam doubles title with partner-in-crime and best mate Thanasi Kokkinakis got many thinking he had crossed the line too often.

Not only did he whip the crowd into an alcohol-fuelled yobbish frenzy during matches, his antics off-court caused more ire.

Kyrgios admitted his on-court interview after winning the men's doubles -- where he told "the ladies of Melbourne" to get ready for Kokkinakis -- had been out of order.

After knocking out the doubles top seeds in an ill-tempered match, Kyrgios claimed their opponents' coach and trainer had wanted a fight in the players' gym.

One doubles opponent, New Zealand's Michael Venus, went on a verbal attack on Kyrgios instead. "At the end of the day he's an absolute knob," he said.

'Luckiest guy in the world'

Tennis great and prominent disability activist Dylan Alcott drew the curtain on a glittering career in the wheelchair quad final.

After 15 Grand Slam singles and eight doubles titles, including a Golden Slam of all four majors and the Paralympics last year, he decided the Australian Open would be his last event.

But Alcott couldn't pull off a fairy-tale ending, losing to second-seeded Dutchman Sam Schroder 7-5, 6-0 on Rod Laver Arena.

"I'm really the luckiest guy in the world, and I didn't need to win today to realise that," he said afterwards, choking back tears.

Don't stop believing

A tournament that began in such chaos ended with two history-making moments.

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Ashleigh Barty became the first Australian to win a singles title in Melbourne's Grand Slam since Chris O'Neil in 1978.

O'Neil was there to witness it and Barty was presented the trophy by all-time great and fellow indigenous tennis icon Evonne Goolagong Cawley in a magical, emotional moment.

Then Rafael Nadal became the first man to win 21 Grand Slams with a victory for the ages, his mightiest ever comeback in a match that lasted 5hr 24min and finished at 1:11 am local time on Monday morning.

Down and almost out against world number two Daniil Medvedev, the Spanish great somehow bullied himself back into contention.

"I don't know how I did it, " said Nadal.

"I just wanted to keep believing until the end."