Alex de Minaur is celebrating what could prove one of the most significant wins of his battling career, downing world No.1-elect Alexander Zverev with a fearless display of attacking tennis to reach the Vienna Open final.

The Australian No.1 played a fabulous deciding tiebreaker, nervelessly brushing off a couple of double faults to keep the pressure on the two-time grand slam champ and eventually prevail 6-4 1-6 7-6 (7-4) to set up a championship match with Carlos Alcaraz at the Wiener Stadthalle.

Saturday's victory had extra importance because it's pushed de Minaur back among the top-eight qualifiers to make the end-of-season men's championship, the ATP Finals, with next week's Paris Masters the last qualifying event in the 'Race to Turin'.

But for de Minaur, it will resonate even more as one of his biggest wins because he'd never beaten Zverev - who'll start his reign as world No.1 when next week's rankings come out - in an individual tournament, his only previous victories having come in early-season teams events and the exhibition that is the Laver Cup.

'I'm super proud, super stoked of how I handled the moment. I was very calm, even though I threw in a couple of doubles there,' beamed de Minaur, pondering how he fought to regain control after his dazzling first set was followed by his serve falling off in the second.

'All in all, I played a very aggressive deciding tiebreak. I played on my terms. I was going to go out swinging and playing the right type of tennis, and that's what made the difference today.'

It was an exceptional display from de Minaur, who'll move back from 10th to No.7 in the world if he can win the final.

He played with a striking front-foot intensity that seemed to shock Zverev, whose mood was fairly tetchy as the Australian was at his terrier best, determined not to let the German settle while uncorking 25 winners in all.

Only when de Minaur's serving deteriorated in the second set did Zverev gain some familiar dominance, but the Sydneysider regrouped superbly in a high-quality decider.

Zverev's irritation became obvious as he served at 5-6 to stay in the match and raged at umpire Arnaud Gabas, who had given him a time violation for his interminable ball-bouncing before serving.

Remarkably, Gabas decided to take back the sanction after Zverev had remonstrated, but the fuss didn't affect de Minaur's focus as he went on to win the first three points of the tiebreak with brilliant shot-making that gave him control even when he coughed up his doubles.

But if beating Zverev was special, defeating Alcaraz, who had beaten Daniil Medvedev 6-4 7-6 (7-2) in the earlier semi-final, looks set to be the ultimate challenge for the Australian.

The pair have met six times, with de Minaur having lost all half-dozen, including at this year's Australian Open.

Asked what it would mean if he could win the ATP 500 event and move closer to a third successive end-of-season Turin appearance, de Minaur smiled: 'It would be a pretty decent week, I would say.

'I'm just happy with the way I'm competing, the way I'm going about my business. Just one foot in front of the other, doing what I can. Ultimately I'm playing some good tennis, looking forward to hopefully finishing strong this season.'