Alexander Zverev will replace Jannik Sinner as the men’s world number one at his earliest opportunity after reaching the quarter-finals in Vienna.

Germany’s Zverev was already guaranteed to finish 2026 as the ATP’s leading player, but made sure he will rise to the summit on Monday with a 6-4 7-5 win over Tallon Griekspoor at the Erste Bank Open.

Zverev, 29, is the second German to reach the pinnacle of the men's tour after Boris Becker in 1991.

The achievement is a testament to his body of work this year, having won two Grand Slam titles and 64 of his 80 matches.

"It's been a wait but sometimes you have to wait for the best things in life," said Zverev, who is the second oldest man to top the rankings for the first time.

"I'm super happy, super thrilled - I have no words for this year."

At the start of the year it seemed unthinkable that anybody other than Sinner or Carlos Alcaraz would become world number one.

But the dominant duo have missed large chunks of this season through injury, opening the door for Zverev - who won the French Open and US Open titles with at least one of the pair absent - to take over.

Going into 2026, Alcaraz led the rankings with 12,050 points, closely followed by Sinner on 11,500.

The duopoly of the pair - who split all of the eight Grand Slam titles in 2024 and 2025 between them - was illustrated by the huge gap to the rest of the field.

Third-ranked Zverev had 5,110 points - closer numerically to the 2,221st player in the rankings than the top two.

Both his major triumphs came without having to face Sinner or Alcaraz, and he did not face a top-10 player until beating Ben Shelton in the New York final.

As the season entered its final stretch, Zverev achieved what many thought was impossible by securing the year-end number one ranking when Alcaraz lost in Shanghai on 12 October.

Zverev knew he still could not overtake Sinner until 2 November at the earliest, but beat Griekspoor to become the first man other than Sinner and Alcaraz to top the rankings since Novak Djokovic in June 2024.

Zverev conceded he would "maybe not" be the world's best player if both his rivals were "healthy and at the top of their game".

But he has efficiently beaten what has been in front of him, recording the greatest season of a career which had threatened to fall short of the lofty expectations placed on him since emerging as a teenage prodigy.

Fery continues to prove himself - and faces Zverev next

Zverev goes on to face British number one Arthur Fery in the quarter-finals - a repeat of their Wimbledon semi-final.

Fery, 24, made an unexpected run to the SW19 last four in July, but continued to prove he belongs among the world's best with a 6-4 5-7 6-4 win over Italy's Lorenzo Musetti in Vienna.

Trailing 4-2 in the decider, Fery showed his mental fortitude by breaking straight back and then overcoming what seemed to be cramp to serve out an impressive victory.

It is easy to forget Fery is still inexperienced at the elite level following his Wimbledon heroics.

Beating former world number five Musetti - now ranked 26th after injury - represents his biggest win by ranking on the regular ATP Tour and provides another opportunity to test himself against the very best.

However, Cameron Norrie fell short of his best victory of the season when world number five Daniil Medvedev saved match point to win their last-16 match.

A frustrating year has seen Norrie drop to 41st in the world rankings and exit each of the past three Grand Slam tournaments in the first round.

But the 31-year-old showed his key attributes - tenacity, athleticism and controlled aggression - to threaten a huge upset against Medvedev.

Third seed Medvedev, fresh from winning the Almaty title last week, was left angrily punching the surface when he fell a break down in the deciding set.

Norrie served for the match at 5-3 40-30, but Medvedev picked off his opponent's serve-volley attempt and fought back to win 4-6 6-3 7-6 (7-1).

Elsewhere, second seed Alcaraz progressed with a 6-1 7-6 (13-11) win over Georgia's Nikoloz Basilashvili.