Federer beat Marin Cilic in the Australian Open final last month to clinch his 20th Grand Slam.
And the 36-year-old enters the Rotterdam Open this week knowing, if he reaches the last four, he will replace Rafael Nadal as the world No 1.
The Swiss star would become the oldest player in ATP Tour history to hold the top spot in what would be yet another outstanding achievement from Federer’s illustrious career.
He will have to come through a field which includes a potential quarter-final match-up against Stan Wawrinka in order to create history.
And Zverev, who could face Federer in the semi-final, admits he continues to be amazed by what the world No 2 continues to achieve.
“It’s great,” Zverev told ATP World Tour’s official website.
“He might be the world No 1 after the week so it’s obviously great to see him with such success still.
“I don’t think even he could have expected that 13/14 months ago when he was outside the top 10, winning three majors in the last five.
“It’s great so I wish him the best of luck and hopefully he can get to the semi-finals and we’ll see how everything else will go.”
Federer gets his tournament underway Tuesday morning (9am GMT) when he faces Belgian qualifier Ruben Bemelmans.