Robbie Williams says it's scary being a father and he sometimes fears he isn't up to the task.

The 'Angels' singer, admitted he worries about doing a good job of raising his 13-month-old daughter Theodora - who he had with his actress wife Ayda Field - as he is barely able to take care of himself, but claims his latest track 'Go Gentle' was written as life-long vow to look after his child as best he can.

Robbie explained: '''Go Gentle' is a promise I'm making to my daughter. It was written when she first arrived on the planet and I'd been a selfish pop star for most of my life and then all of a sudden I've been asked to take care of this whole person.

''I still am scared that I'm not up to the task! I'm doing a good job of being dad but it's scary, you have to look after this person for the whole of their life, I'm not very good at even looking after me!''

The 39-year-old pop star also admitted he often becomes envious of other singer's his age, but is a huge fan of Michael Buble because of his old musical style.

In an interview with British radio station Magic, Robbie mused: ''Anyone that's my age and doing my job, I invariably don't like them because I'm competitive and jealous and petty but with Michael it's different. He's the link to a glamorous past that I wish I'd have been part of. He's the pro's pro I love him to bits!''

Meanwhile, Robbie is set to launch his second big band album 'Swings Both Ways' with a special show at the London Palladium in November.