A loudmouthed DJ warming up the crowd before an advance screening of “Monster-in-Law” in Kansas City broke the ice with a few questions.

“Who’s here to see Jennifer Lopez?”

Dead silence.

“OK. Who’s here to see Jane Fonda?”

Thunderous applause.

Fonda may have been spit upon by a Vietnam War veteran at a recent K.C. book signing, but apparently the public still adores her.

That is not the response shared by her character’s prospective daughter-in-law in “Monster-in-Law,” Fonda’s first movie after a 15-year hiatus. Co-star Lopez portrays Charlie, a hardworking but somewhat directionless woman who becomes smitten with Kevin (Michael Vartan), a handsome doctor. When the pair begins to get serious, Kevin decides to introduce Charlie to his mother, Viola (Fonda), a revered talk show host who had an on-air breakdown after being replaced by someone who could “appeal to a younger demographic.”

Viola takes an instant dislike to Charlie (“My son the brilliant surgeon is going to marry a temp”), and ultimately devises an Iago-like scheme to separate the newly engaged couple. Things grow even uglier when Charlie figures out the plan and wages her own counter-strike.

Viola’s wise-cracking assistant (Wanda Sykes) predicts, “This will end badly.”

Jane Fonda, left, and Jennifer Lopez wage a war of the wills in the comedy Monster-in-Law.

Actually, this crowd-pleasing comedy gets better as it goes along. Despite wallowing in the dopey trappings of a paint-by-numbers genre — the rash of ’60s pop songs, the gay male best friend (Adam Scott), an ex-girlfriend who tries to seduce the heroine’s fiance — the picture generates momentum once the stars go head-to-head.

While few will compare Fonda’s work here with her Oscar-meriting performances in “Klute” or “Coming Home,” she gives the movie the kind of cinematic “oomph” only a surly veteran can muster. Her name-dropping, alcoholic, multiple-divorced character is enjoyable to watch even when her performance veers into overacting. It’s a really similar career role to Diane Keaton’s lauded turn in “Something’s Gotta Give” — minus the nudity.

Credit the 67-year-old actress (who was already in her 30s when she made “Barbarella”) for not trying to disguise her age. There are no soft-focus filters or lack of close-ups employed. Fonda embraces her return to the screen with few regards to vanity.

Her cast mates are a mixed lot, however. Lopez floats by on her gentle charisma, even when it’s hard to digest the notoriously pampered diva as a good-hearted working girl.

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Sykes shows up primarily to deliver one-liners. Her presence is a necessity, because without her PG-13-rated mouth the movie would manifest little edge.

The ultra-bland Vartan (TV’s “Alias) barely registers. It’s hard to fathom that there is an actor out there who is better looking and fields even less charisma than Paul Walker.

Although Fonda will be forever demonized as an anti-war wacko, she still comes across as the more likable figure than Lopez, whose film career has become a running joke following the lethal cocktail of poor project choices and press overexposure.

The odd part is that audience members who buy a ticket to “Monster-in-Law” may find it easier to forgive Fonda for her disastrous 1972 trip to North Vietnam than Lopez for starring in “Gigli.”