Roger Federer may be known by many as the GOAT, but on Monday morning he spent time playing tennis on a boat.

Federer re-affirmed his position as the greatest of all time with victory over Rafael Nadal in the final of the Australian Open earlier this year and there is a sense of anticipation over what he can do next.

But fans in Prague did not have long to wait to see him in action again as the Swiss star took part in a game of miniature tennis on the Vltava River.

Tomas Berdych serves to Roger Federer as they play tennis on a boat on Monday morning

Federer wears a suit and pretends to play his tennis racket like a guitar on the boat

The two fired shots back and forth as they sailed and played on Prague's Vltava river

They posed for photos on the boat as people watched on from one of Prague's many bridges

The 35-year-old faced off against Czech native Tomas Berdych as they began the countdown to the inaugural Laver Cup.

Federer and Berdych could be seen firing the ball back and forth on a small boat as a crowd watched on from one of Prague's many bridges.

The duo clearly had to be wary of striking the ball over the sides as they dealt with playing on a court that was much smaller than either would have been accustomed to.

A crowd gathered to see the Australian Open winner take part in the unique contest

Federer dealt well with the conditions, which included a smaller than standard court

The two were promoting the inaugural edition of the Laver Cup, which will take place in Prague

They were also able to take in some of the sights of the historic city, commonly regarded as one of the finest tourist destinations in Europe.

And the former world No 1 revealed he had been taken aback by his visit to Prague.

He said: 'I've played in some amazing places and this ranks up there because of the beauty of the city.'

The Laver Cup takes place at Prague's O2 Arena between September 22 and 24, 2017. It is a team-based tournament, with six players from Europe facing off against six from the rest of the world.

Federer (right) has undergone a career renaissance after winning the Australian Open