Dad and dude a real odd couple in 'Due Date'

On the heels of last year's "The Hangover" - Hollywood's most profitable R-rated comedy - director Todd Phillips delivers "Due Date," in which an uptight expectant father and an insufferable noodge (with a small dog, nice touch) travel together cross country in a race against childbirth. The rather treadless concept upon which "Due Date" rolls - the Odd Couple takes a road trip - has been done so many times we can't even count, but what's really missing here is the kind of interpersonal venom that would have made it hilarious.

What will likely dawn on the viewer long before the humorless Peter Highman (Robert Downey Jr.) and the clueless Ethan Tremblay (Zach Galifianakis) hit the road is that Downey and Galifiankis could easily have changed places: Downey is adept at mixing irritable and charming and has spent a career playing smart-alecky characters; Galifianakis, a very original personality, can certainly play the uptight, weird and easily disturbed. Without a more clearly defined clash of characters, the movie lacks focus and tension. There are laughs, but they feel like speed bumps.

From the beginning of his career, Phillips has recycled a single winning comedy formula: unfortunate things happening to unlovable people. But before Peter and Ethan even start their trip from Atlanta to Los Angeles - so the nervous father-to-be can be with his wife (Michelle Monaghan) for the arrival of their first child - it's clear the odd-coupling is too tepid. What happened to the overage frat boys of "Hangover'' was Las Vegas. What happens to Peter and Ethan in "Due Date" is each other. And it's not that awful. Or awful enough.