Now that Alexander Payne has made four films (“Citizen Ruth,” “Election,” “About Schmidt” and the new “Sideways”) that have all been excellent, we can officially declare him one of the best directors currently working. A 1.000 batting average is nothing to sneeze at. This is someone you need to pay attention to.

His films aren’t as eye-catching as David Fincher’s or Wes Anderson’s, to name two other relatively new directors with excellent winning streaks. But they crackle with subversive wit while investigating serious themes that most directors wouldn’t know how to address without becoming lost in a morass of self-importance. “About Schmidt” showed an aging man realizing he’d outlived his usefulness … yet it also showed Kathy Bates naked. Obviously, Payne knows how to mix his comedy with his drama, and there’s always a sweet side to it.

Co-writing with Jim Taylor, as always, and adapting Rex Pickett’s novel, Payne gives us another complicated, befuddled protagonist in Miles Raymond (Paul Giamatti). Miles is a would-be novelist, recently divorced, more than a little rumpled, and somewhat useless when it comes to dependability. His hobby is wine, which he loves to discuss, debate and (especially) drink.

His best friend, a semi-employed actor named Jack (Thomas Haden Church), is getting married in a week, so the two drive to California’s wine country for a few days of imbibing and other pre-nuptial debauchery.

Jack’s a piece of work, too, crass in his speech and extremely laid-back, an aging party animal whose 40-year-old body hasn’t yet informed his libido that it’s time to calm down. They’re a fine pair, Miles and Jack, one too neurotic to have a one-night stand, the other so intent on it, despite being already engaged, that he can’t think of anything else.

They meet two women in wine country, a waitress named Maya (Virginia Madsen) whom Miles has always had a crush on, and Stephanie (Sandra Oh), one of many people in the area employed by a winery. Jack and Stephanie hook up almost immediately, but Miles’ timidity and frustration act as barriers between him and Maya. The fact that Jack is getting married in a week remains unspoken, and both women believe Miles’ epic novel “The Day After Yesterday” is about to be published when in fact all presses have rejected it. And so begins a week of deceit.

As expected, there are serious themes at play here, including the importance of honesty with oneself as well as one’s associates, and there is a good deal of introspection on Miles’ part. He cites his favorite wine-making grape as being a particularly high-maintenance variety of pinot that is “thin-skinned and temperamental”; the viewer understands that Miles has chosen a grape that is exactly like himself.

But the movie remains consistently funny, too, due in large part to Church’s daft performance as the blunt-spoken Jack, a combination of whacked-out writing and an excellent deadpan delivery. Giamatti, a virtuoso of nervous self-loathing (witness his performance as Harvey Pekar in “American Splendor”), interacts with Church impeccably, and their friendship seems at once believable and too funny to be believed.

Once the week of deceit has turned into a week of learning life lessons, the film has a bit of trouble resolving itself, as if Payne knows where he wants to go but isn’t sure how to get there. When he arrives, though, it is endearing to behold, and we realize we’ve just seen another first-class entry from, yes, one of the best directors currently working.

B+ (2 hrs., 3 min.; R, a lot of F-words, a little violence, some strong sexuality, some horrible nudity.)