Roger Federer says it is no surprise that the world's top players are struggling with injury, as their careers are longer than before.

Injuries no surprise for Federer

Injuries no surprise for Federer

Federer has battled with injury over the last two years, while Rafael Nadal, Novak Djokovic, Stan Wawrinka and Andy Murray have also had similar problems.

Nick Kyrgios has suggested the season is too long, Murray wants a study into why senior players are breaking down, but for Federer it is not rocket science.

Federer is now 36, and says the injury problems simply come from time catching up with them all.

"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."