That is the view of Sky Sports pundit and former British No 1 Annabel Croft.
Federer takes on Zverev in his second match in Group Becker at the ATP World Tour Finals at London (8pm).
With Rafael Nadal pulling out of the tournament through injury yesterday, Federer is the overwhelming favourite to win his eighth title this season.
Both Federer and Zverev won their opening games of the competition on Sunday against American Jack Sock and Croat Marin Cilic respectively.
Croft is backing Federer to come out on top and qualify for the semi-finals.
However, she believes Zverev will take confidence from his victory over the 36-year-old in the final of the Rogers Cup in Montreal in August.
“I’m definitely going to stick with Federer, I picked Federer to come through this one,” Croft said.
“But I do feel as if anybody can beat him in this draw, it possibly could be Zverev.
“Of all the players in the draw, it is only Zverev who has beaten him in 2017.
“He’s only 20 but he has a real class about him.
“He will walk onto that court tonight believing he can beat Roger Federer.”