It's painful for me to witness three outstanding actors waste themselves on slipshod material. That is the case with James Toback's "Two Girls and a Guy," a muddled comedy that pretends to be more than the sum of its parts. What it lacks is the juice and vigor it needs to transcend its relatively stagy premise.

The story begins with two women standing on a typical New York street corner waiting for their boyfriends. They are Carla (Heather Graham), a blonde, sophisticated working girl type, and Lou (Natasha Gregson Wagner), a brassy, streetwise brunette. It turns out that they are both waiting for the same boyfriend, Blake Allen (Robert Downey, Jr.). "You are an unemployed, short liar," as described in more obscene detail by Lou. Then why do the two women hang around him and pester him in his glorious apartment? Why he is irresistibly charming, of course. Blake, however, is a grandstanding actor...and a pathological liar. He's always lying because as an actor, he's entitled to it. Oh, really. And his other excuse is that he needs to check on his mother who may or may not be sick, and whom he restlessly calls. In the meantime, Carla and Lou try to discover what makes this guy tick, and I discovered it after the first twenty minutes - the film drones for another eighty.

"Two Girls and a Guy" starts off quite well with some fine comic timing by Downey - he steals the show. His delivery of lines is succinctly and flawlessly executed. His body language is enormous, as evidenced by his Chaplinesque work in the underrated Chances Are and Chaplin. But his being questioned and pigeonholed by Carla and Lou makes for irritating viewing. They ask him crude questions of little substance that yield little discovery. As played by Downey, Blake is an arrogant S.O.B., who is full of himself and lives on being high and mighty and dishonest with women. Didn't Carla and Lou suspect such mischievous behavior from the start?

I could live without certain elements in "Two Girls and a Guy" that downplay its comical, dramatic rhythms. A gratuitous sex scene between Carla and Blake is just marking time. That Blake doesn't touch Lou, except for a little peck on the cheek, elicits discomfort at the screenwriting level since he claims to love both women passionately. And then there's Lou's suggestion for a three-way relationship that never builds to anything. Lou and Carla also turn the tables on Blake by admitting their own sexual trysts - an uninventive method of eliciting sympathy for Blake. The final dramatic conclusion feels unnecessary and eradicates the film's central theme of deception.

Robert Downey, Jr. is still superb to watch - look at the scene where he stares at himself in the mirror and asks, "Why do you do this?" Heather Graham is also a delight playing a mature, refined woman with class (very different from her Rollergirl character in "Boogie Nights"). Only Wagner falls short despite some hysterical scenes where she's describing the sincerity of Denzel Washington and the dishonesty of Clarence Thomas. Nevertheless, she does start to grate one's nerves after a while.

"Two Girls and a Guy" is murkily photographed and unevenly scripted with brief allusions to a superior, similar work, Truffaut's "Jules and Jim." Writer-director James Toback ("The Pick-up Artist") seems afraid of dwelling on the sexual, painfully honest questions that two women would have if they were cheated on by the same boyfriend. The film careens out of control before we realize that its pointless chit-chat aims to be nothing more than pointless chit-chat.