World No 2 Alexander Zverev said he is thrilled with the level of tennis he has displayed this year and thinks his performances have helped quash any doubts about him that arose after a serious ankle injury in 2022.
Zverev, who had an extended spell on the sidelines after damaging his ankle ligaments at the 2022 French Open, returned to his career-high No 2 in the world rankings following his victory in the Paris Masters this month.
The German also won a Masters 1000 title at the Italian Open in May and reached the final of the French Open.
"In 2023, I didn't feel like I was competitive in big events, I was far away from winning them," Zverev told ATP Media ahead of the season-ending ATP Finals.
"Being able to compete and make Grand Slam finals, win Masters 1000 events, that is a big satisfaction to me because there were obviously question marks if I was ever going to do that again after the injury.
"It was the first year where I was competitive again in big events. I'm happy with where I am."
The week-long ATP Finals, which feature the world's best eight singles players and doubles teams, are being staged at the Inalpi Arena in Turin from Sunday.
Zverev will begin his quest for a third title on Monday, taking on world No 9 Andrey Rublev, before facing four-times Grand Slam winner Carlos Alcaraz and Norwegian Casper Ruud.
"I think coming in and playing one of the best eight players in the world straight off is a very difficult thing to do. You have to be focussed, you have to be ready from the get go. I'm looking forward to this week," Zverev said.
Rublev is a "powerful, extremely fast player," he said. "He tries to overpower you. The most important thing against him is to not let him."