Alcaraz roared back on Tuesday to win his first title in nearly eight months at the Japan Open, while his great rival Jannik Sinner announced he's ending his season through injury, a decision that will condemn him to losing the top spot.
It felt poignant on the day when Sinner finally gave up on a 2026 campaign which had begun in such amazing fashion for him but has now ended with a concerning knee injury that Alcaraz should demonstrate he's truly back following his long-standing wrist trouble by defeating Jiri Lehecka 7-6 (7-4) 6-4 in Tokyo.
Yet the news was also monumental for Zverev who's won two grand slams this year amid the woes of the big two. Following Sinner's decision, he's sure to emulate Boris Becker as only the second German to become men's world No.1.
That's because Sinner, who couldn't have been a more dominant No.1 earlier this season as he successfully defended his Wimbledon title, will now forfeit more than 3,000 ranking points while being unable to defend his Paris Masters and ATP Finals triumphs.
Zverev, meanwhile, could afford not to win a single match between now and the end of 2026 and still become only the 30th man to earn the honour of being world No.1.
Alcaraz will be itching to return to that spot, showing his champion's spirit against Czech Lehecka in just his third tournament back despite never being at his best.
"I'm really happy to be able to lift a trophy again. It's been a while and obviously it's extra special after my injury," said the Spaniard.
"It was a tough week that I didn't find my best tennis, my best level, but I did find the good solutions and I think that's what matters in the end.
Meanwhile, Sinner, who's actually beaten Zverev 5-0 in their 2026 meetings, revealed in a post on Instagram he's taken the decision to end his campaign to help his long-term health.Â
"Me, together with the doctors, have decided that I need a course of treatment for my knee, which means that the 2026 season is officially over," he announced.
"I also need to think about my long-term career so I will do everything possible to get back 100 per cent."
But Sinner will clearly be targeting a return by the time the Australian Open, which he won in both 2024 and 2025, comes around.
He had enjoyed a dazzling 2026 season, being on a 30-match winning streak before his meltdown in a second-round capitulation at the French Open amid the Paris heatwave.
His management team said Sinner would follow a course of treatment for inflammation in his knee. "The decision has been made to have the treatment now to give Jannik the necessary time to recover before beginning preparations for 2027," a statement said.
