Roger Federer is the closest the professional tennis circuit has to a wise elder.
That's why it's worth listening when the Swiss master says he has a theory that explains the unprecedented series of results at this year's Australian Open.
More Tennis Videos
Five things I learnt at the Australian Open
Sports writer Scott Spits learns five things from day nine of the Australian Open 2017 in Melbourne.
Unseeded Denis Istomin knocked out Novak Djokovic in the second round, Mischa Zverev knocked over Andy Murray in the fourth and last year's Open champion Angelique Kerber went out early.
Meanwhile several veterans, including Federer himself, plus Venus Williams and Rafael Nadal, have made deep runs in this year's tournament.
![Roger Federer overcame a slow start to reach the quarter-finals.](/web/20170125234117im_/http://www.smh.com.au/content/dam/images/g/t/w/i/i/n/image.related.articleLeadwide.620x349.gty2xx.png/1485315216103.jpg)
Federer's theory: it's the court, stupid.
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.
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.
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.
"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."
Federer is now gunning for his first Open title in five years. In the final four he will face fellow Swiss Stan Wawrinka, who earlier ousted Frenchman Jo-Wilfried Tsonga also in straight sets.
- with AAP