The singer worked with the rapper on the song 'Only You' for her debut album 'From the Roots Up' and while they argued over how it should sound, it made their friendship stronger.
She told BANG Showbiz: ''He challenged me and we've become great friends because of it. And I think I challenged him too, which he's not used to, because his persona is quite a bit of a geezer and I'm quite soft.
''We fought hard. I haven't fought a man as hard as him. He didn't take into consideration that I was a woman at all, I'd pull the card but he was like, 'what?'
''We battled but we came through the other side and made some great music and I think it made our friendship stronger.''
Delilah, 22, added she was in awe of the singer, rapper and film director - real name Ben Drew - for a long time before they met.
She added: ''Plan B is very intense one of the most creative person I know kind of like a mad genius, he's eccentric in his own way, not in a way that you'd catch him wearing a feather boa, but he's a very deep thinker.''
Delilah, Conor Maynard and Rita Ora are working with MasterCard to give fans the opportunity to star in a Priceless Remake of one of their music videos and join them at the BRIT Awards on February 20. To be in with a chance of winning, visit Somethingforthefans.co.uk