World No 3 Alexander Zverev admitted on Saturday that he has "a lot of catching up to do" to challenge Carlos Alcaraz and Jannik Sinner.
The 28-year-old German finished the 2025 season with only one title, in Munich, having been beset by injuries.
He still did enough to bag the No 3 ranking behind Spain's Alcaraz and Italian Sinner, although he trails the dominant pair by more than 6 000 ranking points.
"Of course, No 1 and two are quite far ahead, which was not the case at the end of 2024, when I finished No 2 in the world (behind Sinner)," Zverev said in Sydney, where he is playing the United Cup.
"I feel like I have a lot of catching up to do, but so does the rest of the tour."
While Zverev made the final of the season-opening Australian Open last year, losing to Sinner, he disappointed at the other three Grand Slams and also at the year-end ATP Finals.
Despite this he considers 2025 as a step forward, all things considering.
"I had issues with my body, I had injuries throughout the entire season. So for me, finishing three in the world, I feel like looking back at it, it's still something to be proud of," he said.
"Of course it wasn't the season that I wanted to have," he added. "There weren't the titles that I wanted to have, the big titles especially."
Along with his physical problems, Zverev also struggled with his mental health, taking a one-month break after losing in the first round at Wimbledon.
"I took some vacation, spent time with my friends, then went back to training. Changed the scenario a little bit," he said.
"In a way, losing first round Wimbledon – of course I don't want to lose first round Wimbledon – but in a way it was helpful for me because I could just restart.
"That was a bit of a turning point."
Zverev is spearheading Germany at the mixed-teams United Cup to open his 2026 campaign before heading to Melbourne Park and another crack at an elusive Grand Slam title.
In contrast, Sinner and Alcaraz play only an exhibition against each other in South Korea before the Australian Open, a scenario that would not suit the German.
"Some guys, like Jannik and Carlos, they're just capable of showing up to the Australian Open, playing great tennis straightaway," he said.
"I feel like I'm more of a diesel engine sometimes where I need to get going first, then at some point I'll start playing good tennis. I have to play a preparation tournament."