Roger Federer has again jumped to the defence of Australian duo Nick Kyrgios and Bernard Tomic and believes they are motivated to do well in the sport despite facing criticism for their behaviour on and off court.

It is being suggested that Kyrgios and Tomic, who have both been touted in the past as potential Grand Slam winners, do not love the game enough to fulfil their potential. Both the players in the past have admitted that they do not like the game but play it to earn a living.

A number of current and former players have labelled the former a future world number one, but he is yet to convert his potential into consistent runs into the latter stages of tournaments. Kyrgios won three ATP titles in 2016 and after a title free 2017, he has started the current campaign with a title in Brisbane and a run up to the round of 16 at the Australian Open. Federer is confident that the duo do enjoy their time on the court, especially when they win.

Agassi, the eight-time men's singles Grand Slam winner, had made a similar claim in his autobiography years ago, saying: "I play tennis for a living, even though I hate tennis, hate it with a dark and secret passion, and always have," according to npr.org.

Federer, however, has stated that he does not believe the claim made by Novak Djokovic's coach, especially since he played for 20 years on the professional tour. The Swiss ace, who has also been on the tour for two decades admits that there are times when you don't like the sport, especially when a player has just lost a match and believes that it is the case for all players.

"I believe they [Kyrgios and Tomic] do enjoy their time on the courts sometimes," Federer said, as quoted by Tennis World USA.

"Agassi said the same after he retired and he played for 20-something years. I don't believe him as well, everything that he said in that book. I do believe, for the most part, deep inside of them, somehow they do enjoy their time.

"And there are moments when they do win a match, or there are moments in practice where they actually do enjoy it. Maybe there are moments when things are difficult. When you're packing up the bags and travelling to the next event, or whatever it is," the Swiss ace explained.

"Then it becomes tricky sometimes. But that's the case for everybody. But it's also a question of seeing the glass half-full rather than empty. They still have some potential to fulfil. They know that and it's a question up to them if they want to do it or not."