(CNN) -- World number one Roger Federer has told CNN that he is still motivated to win more titles, despite a hectic year on and off the court which saw him secure both the Wimbledon and French Open titles -- as well as getting married and becoming a father of twin baby daughters.
Questions have been asked about the Swiss in recent weeks, who has suffered a poor end of season following his shock defeat to Juan Martin del Potro in the final of the U.S. Open in September.
However, speaking ahead of next week's ATP World Finals in London, Federer told CNN sports anchor Pedro Pinto that his desire to win more titles and grand slams remains as strong as ever -- despite his domestic life becoming more hectic in recent months.
"Motivation for me is really not a problem because I love tennis too much just to say 'I have won all the slams and two beautiful daughters and a wife -- I'm happy so I'll leave'
"It is not the way I see it at all. I want to stay in tennis for as long as possible -- and as long as my wife allows me too, because obviously she has a big say now!
"My hunger will definitely still be with me to succeed and you can tell when it isn't because I will not step onto the court.
"But it's true to say that I am far more content off the court than I have ever been and there is more to my life than just tennis. The test will come if I am 5-2 down in the third set and trailing 2-0 in sets. Then we will see if my motivation and desire is as strong as it has ever been.
Federer has also spoken about his blossoming friendship with world number two Rafael Nadal -- and has admitted the two players get along very well off the court.
"Rafa is not only a wonderful player but a real nice guy too. We sit on the player council board together -- I am the president and he is the vice-president -- and we discuss what is good for the image of the game.
"We both realise the position and role we play within our sport and we both want to show that you can have a rivalry without it becoming aggresive. When we go on court we want to beat each other, but when we come off the court we are friends again."