That’s according to former British tennis star Greg Rusedski, who was mightily impressed with Federer’s ability to battle back.
The Swiss legend booked his place in the ATP World Tour Finals last four after beating Zverev.
But he needed three sets to do so and cut a frustrated figure in the early stages of the match.
Despite winning the first set, Federer missed opportunities to win the set earlier on and he was also a break up in the second, only for the German to battle back to make it 1-1.
However, Federer’s class came through in the third and final set, eventually winning 7-6, 5-7, 6-1.
And while Rusedski gave Zverev credit for putting up a strong fight, Rusedski went on to explain how Federer proved why he is the best.
“It was an interesting match because if you look at it Zverev was actually the better player in the first set serving 80%, 4-0 up in the tie-break and then loses that set,” Rusedski said.
“Federer is up a break in the second and you’re thinking this could be done in two but Zverev lifts his game and Federer drops his.
“We’re in the third set thinking what’s going to happen here but don’t ever question this man.
“He is the greatest for a reason in my opinion just because he knows how to get the job done, he knows how to change his tactics, he’s done it all.”