World number one Sinner recorded a 7-6 (7-2) 6-2 6-2 victory over American Shelton on Rod Laver Arena – the stage where he claimed his first major title 12 months ago.

Earlier on Friday, an injured Novak Djokovic was forced to retire after losing the first set against world number two Zverev.

Zverev, still bidding for a first major title after losing his previous two finals, now faces a daunting task against the in-form Sinner in Sunday’s final.

“We’ve had some tough matches in the past. Anything can happen,” said Sinner, who has lost four of his six meetings with Zverev.

The women’s final between two-time defending champion Aryna Sabalenka and Madison Keys takes place on Saturday.

Reigning US Open champion Sinner is the youngest man to reach multiple Australian Open finals since Jim Courier in 1993.

Italy’s Sinner has been near-unbeatable in the past 12 months and will go into the final on a 20-match winning streak, having not lost a match since 2 October last year.

Shelton, bidding to reach his first major final, made a confident start by breaking Sinner in the first game of the match – but that was an advantage the 21st seed surrendered three games later after a series of unforced errors.

Shelton, 22, broke again for a 6-5 lead and served for the set but squandered two set points as Sinner dug in to force a tie-break.

Sinner took control from then on, reeling off five straight points to close out the breaker before quickly going up a double break of serve in the second.

The daunting prospect of needing to come back from two sets down against the top seed did not discourage Shelton from entertaining and engaging the crowd.

The American reset admirably to force three break points early in the third set. But, after they went untaken, Sinner struck what proved to be the decisive blow in game five to extinguish Shelton’s hopes of an unlikely fightback.

Despite appearing to limp following an awkward landing, Sinner closed out five straight games to secure victory in two hours 36 minutes.

“There was a lot of tension and I had some slight cramps,” Sinner said afterwards.

“These matches can go very long. Three sets in two-and-a-half hours is quite some time, so I’m happy to finish it in three.”

Sinner’s Australian Open title defence comes against the backdrop of his ongoing doping case, which will be heard at the Court of Arbitration for Sport from 16 April, with the World Anti-Doping Agency seeking a ban of between one and two years.

Shelton struck 18 winners on the way to beating the Russian 7-5 6-1 in 84 minutes in Tokyo.

The 21-year-old’s victory will move him up to a career-high of 15th in the men’s rankings on Monday.

“That meant a lot to me and my team. We have been working really hard since the beginning to build my game and win titles on the ATP Tour,” said Shelton.

“I made some deep runs lately. You see the great champions, they finish weeks off. They win titles, they don’t just get to finals. They are able to maintain their level throughout the week.

“I am not saying I am anywhere there yet, but to be able to do it for one week, put together five matches in a row in Tokyo is really special.”

Success for Burrage

Britain’s Jodie Burrage won her first WTA career doubles title after partnering Jil Teichmann of Switzerland to victory at the Transylvania Open.

The pair defeated France’s Leolia Jeanjean and Valeriya Strakhova of Ukraine 6-1 6-4 in their first tournament together in Romania.

They held the upper hand in the decider, winning 74% of their service points and converting five of their seven break points.

In the singles final, German Tamara Korpatsch claimed her maiden title by beating home hope Elena-Gabriela Ruse 6-3 6-4.

Elsewhere, in the Jasmin Open in Tunisia, second seed Elise Mertens of Belgium won the last 10 games in a row against Italian top seed Jasmine Paolini to come through 6-3 6-0 and retain her title.

In Stockholm, veteran Gael Monfils became only the fourth player older than 37 to win an ATP Tour title when he claimed the BNP Paribas Nordic Open.

The Frenchman beat Russian qualifier Pavel Kotov 4-6 7-6 (6) 6-3 to join Roger Federer, Ivo Karlovic and Feliciano Lopez in achieving the feat.

At the European Open in Antwerp, French teenager Arthur Fils was unable to follow up his shock semi-final win over world number seven Stefanos Tsitsipas on Saturday when he lost out in the decider to Alexander Bublik of Kazakhstan 6-4 6-4.

Britain’s Jamie Murray and New Zealand’s Michael Venus were beaten 6-4 6-1 by Australian duo Rinky Hijikata and Max Purcell in the Japan Open doubles final.

In the Nordic Open doubles final, Great Britain’s Julian Cash and Yuki Bhambri, of India, suffered a 7-6 (10-8) 6-2 defeat against Kazakhstan’s Andrey Golubev and Ukraine’s Denys Molchanov.