Listen to the full interview via the podcast.

Rafael Nadal may be back atop the World Tennis Rankings but judging from his interview with journalist John Carlin in the Financial Times, he is a player who still possesses a sense of his own fragility.

With Nadal set to open his Australian Open account against the ever-controversial Bernard Tomic in a few hours, tonight, we spoke to Carlin, the man who helped pen the Spaniard's autobiography.

"Paradoxically, that sense of his own fragility is precisely where he feels his strength comes from," said Carlin who spoke to Nadal on a midnight trip on the Thames.

"He says this is my way. Other people's way, as he put it, was to be super arrogant and full of themselves. He said 'my way is different'. He said that 'I'm was always beset by doubts and I never go into any game believing that I'm going to win. 'I never regard myself as better than any player that I play against'. He actually said that I don't think I'm very good.'"  

For a player who is top of the World Rankings and has won 13 Grand Slam titles, that is a stunning admission. When Carlin questioned whether Nadal really meant it, the eight-time French Open champion reiterated his point and said that it "motivates him to train harder than anyone" and gives him "an edge".

He added that complacency would be detrimental to his career and that was something drummed into him by his family.

In contrast to his muscular on-court persona, Carlin also revealed that Nadal has a fear of dogs, thunderstorms and "almost always sleeps with the light on".

Carlin described Nadal as a genuinely "nice, courteous and respectul person", a man who is crazy about football and someone who enjoys political discussions.

Assuming Federer does not win another Major and his knees hold up, five more Grand Slam wins will see Nadal take the record for Major wins and Carlin believes failure to overhaul Federer "would not haunt him."