Alcaraz and Sinner could dethrone Zverev as world number one

Alexander Zverev has just played his first match as the new world number one — and he called it one of his worst in recent months.

The German lost 7-5(5), 6-2 to Italy's Lorenzo Musetti in the second round of the Paris Masters.

Zverev reached the top of the ATP rankings after a breakthrough season that included his first two Grand Slam titles at the French Open and the US Open.

But his rise came during an injury-hit year for his two biggest rivals: Carlos Alcaraz and Jannik Sinner.

Both were sidelined for long stretches, which has led to questions about the legitimacy of Zverev's No. 1 status.

Zverev himself acknowledged the scrutiny after the Paris loss.

He argued that he is the first world number one in history who has had to justify his ascension to the top of the rankings.

The German admitted that the constant harassment had 'annoyed' him.

He suggested it was unfair and that he 'deserved' to be where he is.

But the numbers tell a more complicated story.

Zverev became the first year-end world number one without a Masters 1000 title in that same year.

His record against top-ten opponents is poor compared to other recent No. 1s.

And his two Grand Slam titles, while real, feel somewhat hollow in the eyes of the public given the injury absences of Alcaraz and Sinner.

So the question is: how long can Zverev hold the top spot?

The earliest possible date he could lose it is early February 2027, when the rankings are released straight after the Australian Open.

Only Jannik Sinner could pass him on that day.

And it would take near-perfection from the Italian — and an implosion from Zverev.

Here is the math.

Both Sinner and Zverev will lose 800 points from reaching the semi-final of the Australian Open in 2025.

So Sinner needs to win the 2027 Australian Open title to give himself a chance.

Then Sinner needs Zverev's ATP Finals and Australian Open points to add up to less than 630.

For example, one round-robin win (200 points) plus a quarter-final (400 points) would be enough for Sinner to overtake him.

A Zverev semi-final (800 points) would keep him at number one — unless Sinner also adds at least 170 points in January, and more if Zverev scores points in Turin.

For Carlos Alcaraz, the earliest he could retake the throne is a couple of weeks later.

That would require him to retain his Australian Open title and win an ATP 250 event in Rotterdam.

But his margin for error is close to zero.

He would need to win the Paris Masters first, then the ATP Finals.

Alcaraz is currently the highest-ranked player still remaining in the Paris Masters draw.