Kanye West has admitted he was in a ''slightly depressed state'' after forgetting his lyrics at Glastonbury Festival.

The 'Bound 2' hitmaker has opened up about his infamous set at the music extravaganza at Worthy Farm in Somerset, South West England in June 2015 and has compared messing up 'Stronger' to having no job, almost being signed by R. Kelly, but ending up with no money.

Of his performance, he told Annie Mac on BBC Radio One: ''It was incredible. I started off the show and I completely messed up the music. And me, as you can imagine by this phone call, I'm a bit of a perfectionist. So it really put me into a slightly depressed state and it put me back in the position of when I was in high school and I got fired from my job, or when I played my music for R. Kelly and he told me he was going to sign me and then three months later I didn't have any money I couldn't afford a haircut, I couldn't take my girlfriend to the movies and I'm still in my mumma's bedroom, working on beats and I was that close to being signed by R. Kelly...''

The 39-year-old rapper - who has three-year-old daughter North and seven-month-old son Saint with his wife Kim Kardashian West - also admitted he felt extremely ''nervous'' on stage, which never happens to him.

He added: ''I don't usually get nervous, I prepare, I get fully prepared. When that music messed up in the beginning it tapped into my nerves and when you're nervous or vulnerable something special and something different can happen.''

During his explicit set on the Pyramid Stage - that saw him rap in a crane over the top of the crowd - Kanye claimed he was the ''greatest living rock star''.

As he started his performance of his smash hit 'Gold Digger', he said: ''I'm gonna say this now because in 20 years or 30 years I might not get another chance, I'm gonna say it, you are watching the greatest living rock star on the planet.''

Kanye's set was also interrupted by unidentified man - now known to be British comedian Lee Nelson - who ran on stage with a microphone, pretending to rap along before being escorted off the stage.