50 Cent always plays Eminem his music first because his friend has been so successful with all of his own records and knows whether a track will do well or not.
The 'Candy Shop' hitmaker admits his long-time friend is the first person he plays new material to because he feels the 'We Made You' star understands better than any one else what makes a song successful.
He said: "You rarely see Eminem come out. Because people see me so much they feel like I'm the number one hip-hop artist. But I didn't have a record sell 23 million copies. So when I talk to him, I use him as my sound board for balance. I play my music for him to see his response, to see what he thinks.
"He hears everything first, yeah. If you made a record that sold 23 million, you might know something. Wouldn't you agree on that? I play him the records and get his response."
The rapper - real name Curtis Jackson - always asks Eminem for help because they have such different outlooks on life and fame.
He explained in an interview: "Me and Em', we deal with things completely different. He would probably rather not be famous, have finances and have normalcy at the same time. But I understand the fair exchange, in exchange with not being able to walk in the mall and shop, I can afford to buy whatever I want in the mall, that's a fair exchange. I can't walk to go get it but I can have it, and I can send somebody to come get it, that's not bad."