And his scenes with De Niro coast on a deliciously nervous friction that builds slowly. As the unease between the two mounts, it rattles Greg to the point of insanity, while Jack just seems to become calmer. It's a jittery pas de deux that frays your nerves a bit even as it makes you laugh.

Roach's direction isn't always as crisp as it could be; the movie's pace sometimes creeps a little, as it does in Roach's "Austin Powers" comedies. But he does know how to stage discrete comic moments, taking mildly humorous nightmares and turning them into nicely wrought miniatures.

When Greg comes out to breakfast in pajamas borrowed from Jack, his hair teased by sleep into a silly Tintin forelock, he's greeted by the whole extended family (most of whom he hasn't met yet), completely groomed and fully dressed in cheerfully precise prep-casual togs. And Stiller miraculously holds his own during a terrific sight gag, when he walks in on Jinxie squatting demurely on the potty. Greg can't believe what he's seeing, and neither can we: The startled and indignant expression on the cat's face is priceless.

Stiller and De Niro carry the show, but there are some playful comic turns tucked into the movie's margins. Danner, a terrific and largely unsung actress, doesn't have much to do here. But she doesn't make the mistake of playing the blindly accepting wifey, and she's fascinating to watch: She uses her character as a way of elaborating on Jack's. As she quietly looks on, observing the devious high jinks of the man she's married to, her face betrays a subtle variety of emotions: grudging acceptance, amusement, thinly veiled frustration.

And Owen Wilson, as Pam's ex-fiancé -- who has made a killing in the stock market, is the proud owner of a brand-new cathedral-like house and has a master craftsman's talent for woodworking -- ladles out the bull so generously that it gets funnier as the picture moves along. When he reveals to Greg that it was Jesus, the ultimate carpenter, who inspired his love of woodworking, his manner has all the deadpan Middle America earnestness of a cardigan sweater.

But De Niro is, of course, the funniest -- if only because he's not entirely funny. After he badgers Greg into revealing that he prefers dogs to cats, he makes it look as if he's shrugging off the fact that Greg has chosen the "emotionally shallow animal." But of course he hasn't shrugged it off; he has grabbed onto it as if with pincers. De Niro's performance works because it isn't exactly likable -- he's totally at ease with his own jokes, but he's not out to make us feel relaxed. Our uneasiness actually makes his jokes funnier. And you can tell by the impenetrable smirk on his face that he likes it that way.

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