Long competitive, 50 Cent said he would walk away from the mike if his "Curtis" didn't out-sell West's "Graduation" when they hit stores Sept. 11, The New York Daily News reported Friday.

"Let's raise the stakes," said the Queens-born rapper -- whose real name is Curtis Jackson III. "If Kanye West sells more records than 50 Cent ... 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."

West hasn't commented on Jackson's challenge, but he did say, "When my album drops and Fifty's album drops, you're going to get a lot of good music at the same time."