Federer saw off Zverev in three sets last night – 7-6 (8-6), 5-7, 6-1 – in his second round robin match of the ATP World Tour Finals in London.
The victory ensured he booked his place in the last four of the tournament with one match to spare.
Federer’s route to the final was given a slight helping hand, as world number one Rafael Nadal pulled out through injury.
Meanwhile, injuries have cut short Novak Djokovic and Andy Murray’s seasons and prevented their involvement at the 02 Arena.
Federer, who sits on the ATP Player Council, has been impressed with the progress of Zverev, Kyrgios and Shapovalov, and he thinks the trio could one day challenge for Grand Slams.
“I like what I’m seeing with Sascha,” he said.
“I see somebody who is working towards the future.
“I think, yes, of course it’s really important right now to have success. He had that with two massive wins in Rome and Montreal.
“I mean, that’s going to protect his season anyways. The rest sort of is all a bonus.
“What I like to see is I feel like they’re working towards how he could be playing when he’s 23, 24 years old in terms of fitness, planning, organisation, all these things.
“I think that’s nice to see. Now, the future? The thing is it seems like they need a bit more time, the young guys in general, to break through these days.
“Even though I’m really happy to see that there is the likes of Shapovalov or Nick, now also Zverev, making the move early, like what Rafa and Andy did, Novak, Lleyton, all these guys. They were such great teenagers.
“I do see a great upside from all these three guys.”