By JIM SABATASO

[A version of this review appear sin the Aug. 6, 2015, edition of the Rutland Reader.]

Built on an absurd premise with an all-star cast, 7 Days in Hell, which premiered last month on HBO, is an unexpected comedic gift that knows exactly what it wants to be. Directed by Jake Szymanski, the sports mockumentary stars Kit Harrington and Andy Samberg (who also executive produces) as two professional tennis players and bitter rivals slugging it out in a 2001 Wimbledon match that lasts seven days.

Samberg plays Aaron Williams, the adopted brother of Venus and Serena, in what the latter refers to as a “reverse ‘Blind Side.’” Williams is a brash, arrogant bad boy, who’s clearly meant to be a caricature of early-1990s Andre Agassi right down to the ridiculous mullet. Samberg has a way with boneheaded jerks, and he really gives it his all. There are some great comic details here, from his Jordache Jeans endorsement deal to his tomcatting around Las Vegas with a sketchy David Copperfield, who does some great self-parody.

Harrington, meanwhile, plays Charles Poole, a British tennis phenom pushed into the sport by his overbearing and loveless mother, played delightfully by Mary Steenburgen. Like his Jon Snow character from Game of Thrones, Poole also knows nothing; he’s a dimwitted, emotionally stunted man-child, who overuses the word “indubitably” — much to the chagrin of the always-chagrined John McEnroe.

While it’s fun to see Harrington doing something other than brooding in front of gray backgrounds, he doesn’t really leave much of an impression here. He’s entertaining enough, but Samberg is the star of this show.

Szymanski, who’s directed episodes of Saturday Night Live, Brooklyn Nine-Nine, and the bonkers Adult Swim police procedural spoof NTSF:SD:SUV, clearly has experience reining in and focusing silliness. It’s a skill that proves useful as he brings writer Murray Miller’s outrageous script to life.

Miller is a veteran writer for King of the Hill, American Dad, and the cult classic Clone High, and you can see the influence of his time spent on animated comedies in 7 Days in Hell. The joke density is high, piling gag upon gag, as set pieces get more and more outlandish. There’s a shagginess to the story that, left unchecked, would have be resulted in a mess of a film.

Fortunately, Szymanski’s steady hand tempers Miller’s comedic flights of fancy, allowing for diversions that are sometimes superfluous but never aimless. Some of the film’s biggest laughs come from bits that are tangential to the main story. A plot point about a trial segues into a hilarious detour about courtroom sketch artists. Another, about Williams’ line of impossibly designed underwear, provides an amusing and shocking visual running gag. While these bits feel somewhat random, as if they were grafted onto the main story, they are funny enough to justify their inclusion.

The material is aided by a stacked supporting cast of real-life tennis celebrities and journalists, as well as more comedic actors than you can swing a racquet at. Professional athletes can often come off as wooden when reading lines, but everyone here does great work. McEnroe, of course, is a natural in front of the camera, but Chris Evert and Serena Williams also deliver solid performances.

Additional cameos include: Will Forte, Fred Armisen, Lena Dunham, Karen Gillan, a pervy Michael Sheen, a barely recognizable Howie Mandel, a foul-mouthed June Squibb as Queen Elizabeth II, Jon Hamm as the narrator, and even Dolph Lundgren.

At a brisk 45 minutes, 7 Days in Hell feels more like a Saturday Night Live sketch than an actual film. However, that brevity is the project’s saving grace. Something this over the top would have been hard to sustain any longer without becoming self-indulgent and directionless. This film is a well-executed feat of lowbrow, goofball humor — fully aware of its own preposterousness, and funnier than it has any right to be.

CHECK IT OUT: 7 Days in Hell is now streaming on HBO Go, HBO NOW and on-demand services.