Zverev played a serve-volley game, a type rarely seen in the past 10 years as surfaces have slowed and racquet technology has improved – allowing players to stand on the baseline and slug away.

That was helpful both to serve-volleyers and tournament veterans who had experience on older, faster courts, Federer said – players like Venus, Nadal and himself.

The Plexicushion surface used at the Open this year has dramatically increased its speed, Federer said, taking it back to the pace games used to be played at more than a decade ago.

"The game has changed. Tournament directors chose to make it slower. Tennis balls have become slower too. That's OK. I had to adapt my game and play a different kind of style," Federer said in a post-match interview with Channel 7 after beating German Zverev in three sets on Tuesday.

"The conditions [this year] have allowed me to play forward and I thought Mischa (Zverev) did a terrific job this tournament and I hope it's going to inspire more players to do that in the future," Federer said.

In a later press conference, Federer expanded on his theory.

"I think with faster conditions, the older generation, I'm saying like anything before 2005, they are used to faster courts. From that moment on, it was a switch. Maybe it was shortly before that. I'm not sure. But we had to grow up in faster conditions.

"Everything changed as time went by. I think if you look at also Venus, she loves the fast courts. She always has. I think it just is natural for her to play well on this surface because maybe there's less thinking going on, you just play with instinct. That's maybe what older guys can do very well because they don't get frustrated in faster conditions."