50 Cent has vowed to quit music if Kanye West outsells him.
The two hip-hop stars new albums - 50's 'Curtis' and West's 'Graduation - are both released on September 11 and 50 is so confident he will win the sales war he is willing to gamble his future.
50 Cent said: "Let's raise the stakes.
"If Kanye West sells more records than 50 Cent on September 11, I'll no longer perform music. I'll write music and work with my other artists, but I won't put out any more solo albums.
"They would like to see Kanye West give me a problem because I've worked myself into a space where I've become the favourite. Everybody roots for the underdog when he goes against the favourite."
West's last album 'Late Registration' has so far sold 2.8 million - far less than 50 Cent's 'Get Rich or Die Tryin'?' which has sold almost 8 million.
50 went on to claim West's record label will even buy his album to bolster sales.
He told SOHH.com: "And I bet this: When Kanye West's sales come in, he's gonna have a 70 per cent decrease cause Def Jam is gonna buy records to keep him closer to 50 Cent.
"So watch the first week and then watch the second week. Watch his a** drop off the planet."
The Queens-born rapper - real name Curtis Jackson III - has also challenged West to a live TV debate, but his rival snubbed the showdown.
50 Cent said: "I accept the challenge. Kanye, he's not going to want to show up."
When asked about the challenge at the MTV Video Music Award nominations, West said: "What am I going to debate about? I thought it was the stupidest thing. When my album drops and 50's album drops, you're going to get a lot of good music at the same time."