Alexander Zverev becomes world No. 1 amid doubts over how he got there

No men's singles world No. 1 coronation has been this scrutinised since the turn of the century. That Alexander Zverev would ascend the throne before 2026-end was preordained. His reign is being questioned because of the circumstances causing it.

Jannik Sinner and Carlos Alcaraz, the two true captivators in tennis today, missed big chunks of a punishingly hectic season. But even beyond them, Zverev benefited from considerably weakened fields, especially so when he broke his Grand Slam jinx to win the French Open.

To worsen his case, Zverev made a losing start as No. 1, going down 6-7 (5), 2-6 to Lorenzo Musetti at the Paris Masters. Four men before him had lost their first match after becoming numero uno, though none in straight sets.

Zverev remained defiant. "I don't think anybody had to explain themselves as much as I had to do in the last couple of days, which for me, is annoying, to be honest," he said after the defeat. "I feel like I'm the only world number one in tennis history that has to explain why it's okay for me to be world number one, which I find quite difficult, because I think I deserve to be where I am, even though I lost today." The statistics paint a different picture.

Before Musetti, Zverev succumbed to Alex de Minaur at the Vienna Open. It was his ninth loss of 2026 in 12 matches against top-10 opponents. No year-end world No. 1 has had a win percentage as low as 25 versus top-10 players in a season.

The 29-year-old German will have a last shot at improving that percentage at the ATP Finals in Turin, Italy. Days before the tournament begins, tennis journalist Ben Rothenberg reported a fresh lawsuit for Zverev. Former partner Brenda Patea is contesting his claims of "proven innocence" in a domestic abuse case that continues to tarnish his reputation off the court.

On court, in Turin, he won't have to contend with Sinner, who is still recovering from his right knee injury. Nor will Zverev meet Novak Djokovic, who failed to qualify for just the second time in 20 seasons when fit. Alcaraz remains the primary stumbling block.

The Spaniard has stylishly shrugged off a 139-day wrist injury layoff. He has regained the kind of form that made him the most electrifying presence on Tour. After an impressive US Open campaign, Alcaraz has claimed titles in Tokyo, Vienna and Paris.

Barring a Round-of-32 upset to Zizou Bergs at the Shanghai Masters, the 23-year-old has played flawlessly. He arrives in Turin with a nine-match indoor winning streak. Alcaraz has set his sights on a maiden ATP Finals title.

Soon after avenging his US Open loss to Ben Shelton at the Paris Masters final, he said: "This is a tournament (ATP Finals) that I really want to win one day. I'm going to go this year with a lot of confidence, with a lot of information in my bag to do the things that I really wanted to improve and be better in that tournament, and I'm going to go for it." The second seed has been practising with a taped knee but downplayed injury concerns.

"I would say I have just been playing a lot of matches in not too many days and they have been physically demanding matches," Alcaraz said. "There are some problems that came up which are normal I would say for a tennis player.

Right now I am just taking care of my preparation and I am feeling good." He has been drawn in the Ivan Lendl Group along with Daniil Medvedev, Flavio Cobolli and Frances Tiafoe. Zverev, thus, would not face Alcaraz before the knockout stage.

But that doesn't mean he'll breathe easy in the group stage. "I think we shouldn't disrespect anybody," Zverev said on whether he'll be the tournament favourite. "I don't think about Carlos right now. I think about these three young gentlemen," referring to John McEnroe Group rivals Shelton, Arthur Fils and Rafael Jodar.

Cobolli, Fils, Tiafoe and Jodar are all making their ATP Finals debuts. They all have the game to unsettle Zverev on their day. And so the top seed, who is seeking his third title at the event, is keeping his expectations suitably realistic.

"I will have fun playing here. I will enjoy being on this court. I will never take it for granted again to be at a spot with the best eight players in the world." ATP Finals group stage, 6:30pm onwards, Live on FanCode 78.3: Alexander Zverev's win percentage this year.

If he loses even one match at the ATP Finals, it will be the lowest win percentage for a year-end men's world No. 1 this century.