"STANDING UP, FALLING DOWN": Crystal's best work in this painful, funny sleeper

* * * 1/2 (out of four)

If you’re a fan of Billy Crystal, you really ought to see “Standing Up, Falling Down.”

Directorial debut for industry newcomer Matt Ratner, this charming, low-key indie premiered at last year’s Tribeca Film Festival and is now available online. It features what may be Crystal’s finest performance -- but he is not the lead.

That would be “Parks and Rec’s” Ben Schwartz, playing a failed stand-up comic who, at the embarrassing age of 34, returns from L.A. to live with his parents in their Long Island home.

Schwartz’s Scott has somehow not yet found his way in life when he strikes up an unlikely friendship with his aging dermatologist.

At first, this relationship seems to be exactly what the young man does NOT need. Played by Crystal, the eccentric skin doctor is a bit of slacker, a very hard drinker and an occasional stoner with a lot of baggage: he’s lost two wives; his estranged son refuses to talk to him; and he spends his spare time doing karaoke at the local dive, making blueberry pancakes at all hours and watching reruns of 35-year-old Met games.

But for all his downbeat exterior, Marty is a man who’s learned a lot from his broken life. Refusing to be crushed by suffering and defeat, he’s also something of cheerleader for Scott, whose own father and snarky sister are, to say the least, not supportive.

More important, Scott seems to be about the age of Marty’s absent son; and so without the script being too maudlin or obvious about it, we can see that this friendship actually offers hope and healing for both damaged men.

Since Marty is outspoken, rude and sarcastic, Crystal gets to do all that funny stuff he’s so good at; but Ratner’s excellent direction also capitalizes on the undertone of hurt and melancholy that runs through much of this comic’s best work (i.e., “When Harry Met Sally,” “Hamlet,” “Forget Paris,” “Mr. Saturday Night”).

Schwartz, meanwhile, makes Scott very empathetic despite his hapless lifestyle. His insulting sister is nicely played by Grace Mummer (Meryl Streep’s daughter), with fine additional work from Eloise Mumford as Scott’s former flame; Caitlin McGee as a late-appearing bolt of cinematic lightning; and Nate Corddry (Rob’s bro) as Marty’s adamantine son.

The script by Peter Hoare -- who appears briefly in photos as the subject of an early funeral -- is peppered with sharp, funny, realistic dialog; it also provides enormous closure at the end -- all the more surprising, in view of some late-film developments that feel downright disastrous.

Perhaps most memorable is Marty’s repeated assertion that “regret is real,” one of the few true constants in life -- a philosophical nugget that convincingly urges us to both seize the day and accept our many failings.

As the experienced elder imparts such wisdom to his younger counterpart, “Standing Up” reminded me a bit of “Tuesdays with Morrie.”

Except with more pot and F-bombs.

“Standing Up, Falling Down,”

directed by Matt Ratner

Run time: 91 min.

Not yet rated; strong language and some sexuality