Melbourne - Tennis's old guard has staged a surprise revival at the Australian Open, with some wondering whether faster court conditions are the reason.
Fernando Verdasco moaned that Rod Laver Arena was playing like "indoor carpet in the 1980s", but not everyone is complaining.
Roger Federer, 35, has a real chance of winning his first Grand Slam title in five years after reaching the semi-finals, playing tennis of vintage quality.
Venus Williams, the senior women's player at 36, hasn't dropped a set en route to becoming the oldest female Slam semi-finalist since Martina Navratilova in 1994.
After her sister Serena, 35, also reached the last four, it marks the first Grand Slam in the Open era that two women aged 35 or older have made the semi-finals.
Former teenage prodigy Mirjana Lucic-Baroni has also rolled back the years by reaching the semis aged 34 - 18 years after her last appearance in a Grand Slam's final four.
Along the way, defence-minded top seed Andy Murray was upset by serve-volleyer Mischa Zverev, and six-time champion Novak Djokovic lost to 117th-ranked Denis Istomin.
It has made for the most unpredictable Grand Slam tournament of recent times, with few willing to forecast what will unfold over the last few days.
Federer said his return from a six-month injury break may have been helped by a speedier centre court, which keeps points shorter and rewards attacking play.
He said older players will have grown up playing on faster courts, making them instinctively attuned to the quicker movement of the ball.
'THAT'S NOT TENNIS'
"The older generation, I'm saying like anything before 2005, they are used to faster courts. From that moment on, it was a switch," Federer said.
"I remember my indoor courts that I used to play on in Switzerland, they were lightning. I mean, I was playing on carpet or something like this (floor) that was shiny.
"You hit a slice, you could stay on the baseline, you knew it was always going to come to you. Then everything changed as time went by."
Venus Williams said she liked a court that was "playable" - where winners, or what should be winners, don't come back every time, prolonging the rally.
"I think the courts have to be not too slow, not too fast. It's got to be playable," she said. "You don't want every ball to come back.
"At some point there should be a winner. If you're hitting through the court and the ball just sits, that's not tennis. It should go through the court."
Federer agreed that the older Williams sister seemed at home on the faster courts as she cuts a swathe through the draw.
"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," he said.
"That's maybe what older guys can do very well because they don't get frustrated in faster conditions. It's also an art to learn that.
"You see with Zverev, who was able to attack the net all the time, not getting frustrated."
Federer added: "Maybe it has helped me, too, in my comeback. No doubt about it."