Father Time catching up with tennis stars

Nick Kyrgios says the tennis season is too long, while Andy Murray has called for a study into why senior stars are suddenly breaking down as four of the sport's Big Five race the clock to be fit for the Australian Open.

But Roger Federer says it's not rocket science why his chief rivals Rafael Nadal, Novak Djokovic, Stan Wawrinka and Murray are all battling injuries less than two weeks out from the year's first grand slam in Melbourne.

Djokovic (elbow), Wawrinka (knee) and Murray (hip) haven't played competitively since Wimbledon, while Nadal, if he starts, will enter the Open with just one tour match under his belt in two months as he also fights to overcome a knee injury.

All up, 12 of the world's top 20 suffered serious injuries in 2017, but it comes as no surprise to Federer.

The 36-year-old Swiss pointed out at the season-ending championships in London that age was merely catching up with most of the sport's biggest names.

"Shave 10 years off our age and we probably will do better," Federer said.

"A lot of the guys are just touching 30-plus, you know. Back in the day, at 30, a lot of guys were retiring - Edberg, Sampras.

"It was like normal at 29, 32, to start looking towards the end of your career. Now you guys expect everybody to play till 36.

"When somebody is injured at 31, it's like, 'Oh my God, how is this possible?'

"Actually, it's a normal thing."

Federer, who enjoyed an incredible renaissance after spending the last six months of 2016 rehabilitating from knee surgery, agrees with Murray that lengthy breaks from the game are the only way to extend a career.

But, unlike most, the pragmatic Swiss refuses to blame brutal hard courts or the gruelling length of the season for the rising injury toll.

Interestingly, the single-handed maestro also believes double-handed backhands can be crippling.

"(A) wrist (injury) to me is not something that comes from overplaying, especially if it's your left hand," Federer said.

"That's just a move I can't relate to because I don't play double-handed.

"From what I've been told, the wrist is always in a troubled position with that flicking that's going on more and more these days.

"I think Andy (Murray) even broke his wrist. Maybe that was something else, I'm not sure. Del Potro has had three of them. I think these things tend to happen."