Ben Stiller's acting envious of Jack Black, and it's not because he covets his role in Tenacious D.

Stiller's starring alongside the "Shallow Hal" funnyman in "Envy," in which the two play best friends divided by the invention of Vaporizer, a spray that makes poop disappear.

Stiller plays Tim — friend, neighbor and coworker of Black's Nick — who laughs at Nick's "Vaporizer" idea and declines an early invitation to be in on the product before it skyrockets Nick into fame and fortune. A drifter, played by Academy Award-winning actor and Fatboy Slim video dancer Christopher Walken, barges into the situation and fuels Tim's burgeoning jealousy of Nick.

"Envy" is being directed by Barry Levinson ("Rain Man"), and costars Rachel Weisz ("The Mummy Returns"), Amy Poehler ("Saturday Night Live") and Ving Rhames ("Mission: Impossible 2").

Black first rose to prominence with a gut-busting turn as novelist Nick Hornby's record store clerk/ music geek/ Sonic Death Monkey frontman Barry in 2000's "High Fidelity," though by then he had already appeared in supporting roles in movies like "The Cable Guy" and "I Still Know What You Did Last Summer." He also comprises one half of the acoustic musical duo Tenacious D, who starred in their own short-lived HBO series in 1999 and released their debut album last year.

Last year's "Shallow Hal," the first comedy in which Black received top billing, was a bit of a box-office disappointment, though his supporting turn as Colin Hanks' brother in "Orange County" brought him back into the public's good graces. The voice he provided in this year's animated "Ice Age" no doubt proved lucrative as well.

Black co-hosted this year's MTV Movie Awards with Sarah Michelle Gellar and is slated to provide a voice to 2004's animated "Sharkslayer" with Will Smith and Chris Tucker. He first crossed paths with Stiller on the big screen in 1996's "The Cable Guy."

Stiller's upcoming projects include "Duplex," a romantic comedy he recently wrapped with Drew Barrymore that's set for a February release, and the big-screen adaptation of '70s cop show "Starsky & Hutch," which Stiller will also co-produce (see " 'Starsky And Hutch' Director Wants Snoop To Play Huggy Bear"). On top of that, there's "Meet the Fokkers," the long-discussed sequel to 2000's "Meet the Parents" in which he starred as future son-in-law to Robert DeNiro (see "Sequel Mania — The Other Attack Of The Clones").

"Envy" recently began shooting in Los Angeles, according to a statement issued by DreamWorks Pictures, with additional shooting planned for Rio de Janeiro, Brazil. The film is tentatively scheduled to be released sometime next year.