Stormzy has revealed how he prevented Jay-Z from appearing on his song with Ed Sheeran, Take Me Back to London.
The US rapper wanted to appear on the track, but the grime star turned down his "number one hero inspiration" because he thought it was a bad fit.
"I felt proper bad because I was like, 'You're saying no to Jay-Z!'" he told ITV's Jonathan Ross show.
"Jay-Z was super proud and super shocked and taken aback by the fact that this kid told him," he added.
The song, which appears on Sheeran's No. 6 Collaborations Project, went on to top the UK singles chart for five weeks in September and October.
It finds the two Glastonbury headliners reminiscing about their London days, "hitting raves" and ordering "packets of crisps with my pint".
Jay-Z was in the studio as the track came together, Stormzy told Jonathan Ross in an interview that's scheduled to air on Saturday [30 November].
"Before that I loved Take Me Back To London because I thought it was just going to be me and Ed," he said, "and then Ed was like, 'Jay is getting on it.'
"It blew my mind. Jay-Z is my number one hero inspiration.
"We got into the studio and we were writing for this song and then he just stops the music and he said, 'Tell me about London, I need some inspiration.'"
Stormzy said he and his manager had a "powerful, beautiful" conversation, "talking about everything from black culture, community [to] music, his journey, my journey...
"It was the greatest conversation of my life."
'He couldn't believe it'
Stormzy continued: "At the end he's smiling, we were probably talking for an hour and he goes, 'So what do you think of the song?'
"I was like, 'I love this song but you being on the song changes everything'.
He went on: "'If you didn't ask me this, I would have just written my verse and we would have done it and I would have never questioned it, but now that you've asked me, no.'
"I was like, 'I know how it goes, Mr Z. You are the most brilliant, busy man and I will probably never get this opportunity ever again but hand on my heart, I don't think this is the right song for us. I don't know why I'm saying this to you but this is not the song.'"
Describing Jay-Z's astonished response, Stormzy said: "He fully understood [but] he couldn't believe that I did it."
But the session wasn't a complete bust: Footage of Jay-Z and Stormzy's conversation was used in the introductory video for Stormzy's historic Glastonbury performance this summer.
The rapper recently announced his second album, Heavy Is The Head, will be released on 13 December. He has also revealed plans for an extensive, 55-date world tour in 2020, with shows scheduled in the UK, US, Canada, China, Korea, Australia, New Zealand, Nigeria and Ghana.
HEAVY IS THE HEAD - THE WORLD TOUR 2020 #HITH— HEAVY IS THE HEAD (@stormzy) November 29, 2019
Tickets on sale 9am your LOCAL time Friday 6th Dec 2019. Dubai on-sale Wednesday 4th 8am. For early access to tix (ex. Asia & Africa) pre-order ‘Heavy Is The Head' from my official store by 9AM UK Time 3rd Dec https://t.co/CgwCD9hRd6 pic.twitter.com/6TRx1MGxGN
The Jonathan Ross Show will air on Saturday, 30 November at 22:10 on ITV.