Zverev’s first week as world No. 1 opens on the ball he just complained about in public.

The 29-year-old German received the trophy on Court Central alongside ATP chairman Andrea Gaudenzi and tournament director Cedric Pioline, becoming the 30th man to top the rankings and only the second German player to do so. “It’s incredibly special to celebrate it here in Paris, where a couple of months ago I won my first Grand Slam title,” he said at the ceremony.

That maiden Grand Slam came at the French Open, and a US Open title in September sealed the season that carried him past Jannik Sinner at the top of the men’s game.

Two days earlier in Vienna the mood had been very different. Zverev lost his semi-final to Alex de Minaur 4-6, 6-1, 6-7 (4-7) on Saturday, audibly unhappy with the Dunlop balls as he fell a break down in the first set.

Read also: Jules Koundé hits back at French fans with blunt message: “You just have to deal with it”

“Do you think it’s normal to play with these balls at a tennis tournament?” he asked the chair umpire, according to Yahoo Sports.

He later extended the complaint to the surface. “The balls are incredibly slow, the court is incredibly slow, and most importantly, the bounce is very, very low,” Zverev said. “De Minaur handles that better, and he was also better than me today.”

An ATP-mandated switch

The problem is that Dunlop is now the ball he will see for the rest of the season. The brand is the official supplier for the entire ATP indoor swing, covering tournaments including the Rolex Paris Masters, the Erste Bank Open in Vienna where he just lost, and the Nitto ATP Finals in Turin.

Pioline has told Tennis365 that the switch is an ATP-wide decision aimed at giving players consistent conditions from Shanghai through to Turin, and that the governing body has set up a mechanism so no tournament is financially penalised for taking on the imposed ball. He framed it as a step for player comfort rather than a concession to individual complaints.

Read also: Liverpool make their position clear on Virgil van Dijk as contract expiry approaches

Musetti waiting in round three

Zverev enters the week as top seed and faces Lorenzo Musetti in the third round, after the Italian edged Hubert Hurkacz 7-6 (3), 7-6 (10) on four match points to earn the meeting.

Read also: Diomande does it again: the half-volley that left Real Madrid’s stars stunned