There can no longer be any doubting Roger Federer is not only the greatest tennis player to live, but one of the finest athletes of all time.At the age of 36, Federer collected no less than his 20th Grand Slam title and his sixth Norman Brookes Challenge Cup at the Australian Open.The Swiss legend saw off the challenge of Marin Cilic, the same man he defeated in last year's Wimbledon final, to write himself into the history books.It was by no means an easy match for Federer on the hard court of Melbourne, though. Although far from one of his five set classics with Rafael Nadal, proceedings went all the way after Cilic responded to both of Federer's set wins.Ultimately, though, there was no stopping the inevitable as a 6-1 romping in the final set saw the Rod Laver Arena rise and salute the greatest. 

Federer wins his 20th Grand Slam

Collecting his latest accolade on court, Federer reflected: “I’m so happy. It’s unbelievable. The fairytale continues for us, for me. After the great year I had last year, it’s incredible. Marin had another great tournament."

Unsurprisingly, his victory has sparked a massive reaction on Twitter and not only from the tennis community.

A number of footballers have tweeted about the GOAT with Rio Ferdinand leading the way.

Rio Ferdinand takes to Twitter

Since hanging up his boots in 2014, the Englishman has pursued a career in punditry as well as furthering his brand '5' which has seen cross paths with Federer before.

Take a look at his post below:

You couldn't have put it better, Rio.

We're not quite sure just how pressurising cooking three courses for the Man Utd legend really is but the point remains, Federer seems to hoard all these trophies with ease.

And it wouldn't be a tweet saluting the 36-year-old without rightly heralding him as the greatest to step on court.

Fans can only hope that Federer will continue to wow us with a few more seasons of brilliance. 

Do you think Roger Federer is the greatest athlete of all time? Have your say in the comments section below.