'Surprised' Federer lauds Murray's extraordinary achievements

17-time Grand Slam champion Roger Federer has saluted 'extraordinary' Andy Murray for surpassing Serbia's Novak Djokovic and becoming the new World number one.

Last month, Murray dethroned Djokovic to earn his first title at the ATP World Tour finals and made sure he remained No. 1 until next season.

By ending Djokovic's 122-week reign, Murray also became the second-oldest player since John Newcombe in 1974 to debut at World No. 1.

The 29-year-old Briton notched up a total of nine titles this year, including a second Wimbledon title and a second Olympic singles gold in Rio de Janeiro.

"I was very surprised just because when a guy starts a season the way Novak does, achieves his dream by winning the French and his fourth Slam in a row, of course there's no way in the world that anybody, even the players, start thinking another guy could actually finish No. 1," Sport24 quoted Federer as saying.

On the other hand, Djokovic clinched this year's Australian and French Open before the Serbian's season went off course.

He made a third-round exit at Wimbledon, a first-round upset at the Rio Olympics and final defeat to Stan Wawrinka at the US Open before losing the numero one ranking to Murray.

Downplaying Djokovic's dip in form, Federer insisted that the Serb didn't play too bad in the second-half of the season and he instead just failed to perform extraordinary which Murray did.

"Novak, let's be honest, actually didn't play too bad in the second half. He won Toronto. He played finals in many other tournaments: US Open, the World Tour Finals. You would think that was going to be enough, but what it required was something extraordinary, and Murray was able to deliver that, and that's where I take my hat off," he added.

In July, Federer ruled himself out of the rest of the season to recover fully from his injury, which got aggravated during his semifinal defeat to Milos Raonic in Wimbledon.

The Swiss is now preparing to make a return in January's Hopman Cup by representing the Indian Aces in the International Premier Tennis League (IPTL).