"He was literally clinging by his fingertips to the White Cliffs of Dover wasn't he? And a lot of people were willing him to fall but not me."
Bieber isn't the only young star that John has been rooting for in recent years. The 68-year-old musician makes time for some of his other favourite singers, even inviting them over to his house so he can give them advice.
"I try and keep up with Tom Odell, Sam Smith and James Blake," he explained. "I've had them all here for lunch or tea.
"I have no agenda with them and I don't manage them. I've just said, 'Listen, I'm always here, use me if you want'.
"People were like that to me. George Harrison sent me telegrams and Leon Russell was so sweet to me. These were people I loved and admired and it made the difference."
John is currently promoting his new album Wonderful Crazy Night and despite having a host of hit records under his belt, he shows no signs of slowing down just yet.
He still feels passionate about making music and feels he has plenty more to achieve in his career.
"I'm not finished yet!" John exclaimed. "I'm more interested in keeping going. I have so much more to do.
"I'm not nostalgic. I don't think about my place in music history at all.
"I know my own worth as a musician. And if I know that I'm a good musician and a good writer and a good artist, that's all that matters to me.
"It's up to others to judge me but I know the piano playing on my new record is pretty f**king special!
"You have to keep trying to improve as you get older. Look at Leonard Cohen. That comeback at 75 was astonishing."
John also describes Rolling Stones frontman Sir Mick Jagger as an "extraordinary professional" and is full of admiration for his energetic presence on stage, adding he hopes the band continues to tour for many more years.
- WENN