The biggest and best surprise of Sideways is its great and decidedly Oscar-worthy performance from Thomas Haden Church. I'm told he's the guy from Wings, but I can't remember him or the TV show. He was last seen on the big screen, though not by me, in Serial Killing 4 Dummys and George of the Jungle 2. A long while ago, he was the guy you hadn't heard of wedged between Val Kilmer and Kurt Russell in Tombstone. Now, he's up for a Best Supporting Actor Oscar.

So as a semi-retired actor with a broad, familiar-both handsome and unremarkable-face and a shrugging air of the second-rate, he's perfectly cast in Sideways. The choice could have been insulting were it not for Church's grand, sporting and totally guileless performance as Jack. He makes the movie-which is not to say he steals it from Paul Giamatti, who delivers another reliably splendid turn as Miles, the film's protagonist. Church counterbalances Giamatti so graciously, he's both a ballast and a breath of fresh air. In other words, the best supporting actor you could hope for.

With a week to go before Jack's wedding, he and Miles take a trip through California's wine country. Miles-oenophilic alcoholic, failed novelist, reluctant middle-school teacher and Jack's best man (in approximately that order)-wants to get in some wine, some pontification about wine and some golf; to stop worrying about the book his agent hasn't sold; and to nurse the unhealed wound of his not-so-recent divorce. Jack just wants to get laid. Tossing his semi-shaggy hair, talking with the dulcet diction of a pseudo-surfer, twiddling his hands at his sides like a cowboy, Jack is ready for action: "Well, I say, 'Fuck therapy,'" he says early on. "You need to get your joint worked on, Miles."

A buddy movie, yes. One good and unusual thing about Sideways is how Giamatti and Church trade off on being each other's straight man. You'd think Jack, as the womanizing, past-his-prime, frat-boy goofball who chews gum while gulping (never sipping) his wine, will be stuck on "over the top" the whole time only to be levelled periodically with dry zingers from the doubting, pouting Miles. But then Miles starts prattling on about his doomed literary prospects or about over-manipulated Chardonnays with their "too much oak and secondary malolactic fermentation," and Jack has the sense to reply simply, "Huh!"

Church's skill with deadpan is the movie's most savoury flavour. When Jack, so innately accustomed to flattering women, says to Miles' mother over dinner, "This is delicious, Mrs. Raymond, absolutely delicious. Is this chicken?" or, to Miles, "You dick. Why do you have to focus on the negative?" he makes us believe right away that a guy like Jack could make the absolute best of being freshman-year college roommates with Miles and staying friends with him thereafter. Who knows whether Jack really believes Miles will make it as a writer? But he doesn't give up on Miles, even when Miles gives up on himself. At his most selfish, Jack is still touchingly generous: of their joint excursion into hedonism, he pleads, "It's something we should share!" Church's candour is how we know we can trust the movie and allow ourselves to share the characters' indulgences.

As hoped, they meet two women, Maya (Virginia Madsen) and Stephanie (Sandra Oh). Miles descends into nervous wreckage over Maya, and Jack, ever the bachelor partier, pounces on Stephanie. In one tender moment of courtship, Giamatti and Madsen trade eloquent monologues on the virtues of wine: his, while sensitively delivered, seems too rhetorical; hers, a shade too performed (yes, she's nominated too). Church's overall accomplishment, by contrast, feels entirely unburdened, neither too scripted nor overwrought with actorly contortions. On the page, Jack may well read as lifeless and entirely functional-a foil for Miles and not a real person-but in the film, whenever he's off-screen for a while, you want him back.

Giamatti may appear to have done most of the heavy lifting in Sideways, but, without Church spotting him, he'd surely have strained himself.

In an episode of near-self-reflection, trying to justify his cheating ways-and perhaps crying out for help-Jack says, "All I know is, I'm an actor. All I have is my instinct." He's pouting and putting on a little show, but he means it. Church, knowing full well he's not in an Altman film, doesn't bother satirizing or infusing the moment with a smug commentary about Hollywood. He shows great restraint and respect in not winking at the audience.

Which is why Alexander Payne's instinct in transplanting Church from semi-obscurity into his latest film phenomenon seems so astute, and the result seems so unlike the show-offy, somewhat patronizing career resuscitation that Quentin Tarantino performed on John Travolta in Pulp Fiction. For one thing, Church was never that big a star to begin with. Nor is he interested in becoming a fashion statement. That, in itself, deserves an award.

Meanwhile, the matter of Giamatti not being nominated (two years in a row now, remember American Splendor?) is another surprise, and an affront to that actor's growing fan base. People have really started rallying on Giamatti's behalf, including David Poland, who wrote, "In the supporting actor category, the pickings were so slim that Alan Alda got nominated for playing Alan Alda for roughly ten minutes." Not true! First, Alda had at least eleven minutes of screen time in The Aviator, and he played not just himself but a slightly sinister version of himself. Second, those pickings included some pretty respectable performances from Morgan Freeman, Jamie Foxx and Clive Owen. And, of course, this revelation from Thomas Haden Church.

The real Oscar snub, in other words, would be to give the prize to anyone but Church. Giamatti may appear to have done most of the heavy lifting in Sideways, but, without Church spotting him, he'd surely have strained himself. We have no reason to doubt that Giamatti will continue doing the fine character work that has so distinguished-or perhaps undistinguished-his career. Yet, it is fair to ask: What will now become of Church? Will he ever be this good, this winning, again?

Maisonneuve contributing editor Jonathan Kiefer writes about the arts for various publications in San Francisco, where he lives. One of his cats is named after Preston Sturges. Film Flâneur appears every second Friday.