The good news is that the rap superstar granted Yankovic -- who specializes in pop song parodies -- permission to satirize "Lose Yourself," Eminem's Oscar-winning hit from the 2002 film "8 Mile."
But Eminem decided not to let Yankovic make a comic video to support the parody, which is entitled "Couch Potato."
"Eminem was fine with me having the parody on my album," Yankovic, 43, notes. "But he said he was afraid that a Weird Al video might detract from his legacy, that it would somehow make people take him less seriously as an important hip-hop artist.
"I'm grateful to Eminem; he at least let me put it on the album. I have to say I'm extremely disappointed at the same time; frankly, this was going to be the best video that I've ever done."
Yankovic says he disagrees with Eminem's reasons for barring the video. He points out that some of his previous parody hits -- 1984's "Eat It" (Michael Jackson's "Beat It"), 1992's "Smells Like Nirvana" (Nirvana's "Smells Like Teen Spirit") and 1999's "The Saga Begins" (a "Star Wars"-related send-up to the tune of Don McLean's "American Pie") -- resulted in a sales bump for the original songs.
And Nirvana's late Kurt Cobain even commented that he felt he had "made it" because Yankovic had chosen one of his songs to parody.
The accordion-playing Yankovic, who's also won awards as a video director, hopes that Eminem ultimately feels the same way.
"The choice of Eminem was a no brainer," explains Yankovic, who pays royalties to the artists he parodies.
"He's the closest thing we have to a superstar at this point in time. He just dominates the pop market.
"And 'Lose Yourself,' I thought, was a good choice because it's one of his more serious numbers. It works better when you can poke fun at something that's kind of weighty and serious. It would have been redundant to parody his more tongue-in-cheek songs like 'Without Me,' because that's already funny and sort of satirical."
In "Couch Potato," Yankovic raps about watching the TV the same way Eminem raps about making it as a musician in "Lose Yourself." Sample lyric: "If you had one shot/To sit on your lazy butt/And watch all the TV you ever wanted/Until your brain turned to mush/Would you go for it/Or just let it slip?"
"Couch Potato" is the first single from Yankovic's new album, "Poodle Hat," which will be released on May 20.
Following his platinum-selling 1999 set "Running With Scissors," "Poodle Hat" features parodies of Nelly's "Hott in Here," Avril Lavigne's "Complicated," Backstreet Boys' "I Want it That Way" and Billy Joel's "Piano Man."
Yankovic's also wrote a new polka medley on titled "Angry White Boy Polka" that strings together polka-styled versions of songs by the White Stripes, the Hives, the Strokes, Limp Bizkit, Rage Against the Machine, P.O.D., Disturbed and Staind.