Everyone loves seeing Goliath fall, even as we secretly rooted for Golden State to unseat the 1995-96 Chicago Bulls as the winningest single-season team of all time and for the Spurs to stay undefeated at home this NBA season. But in all fairness to the future sweep victims in the Rockets and Grizzlies at the hands of these two Western Conference juggernauts, the only technically beatable conference Goliath right now is the Oklahoma City Thunder. And the Dallas Mavericks are their David.

The Thunder are an oddly constructed bunch consisting of two of the seven best basketball players in the league, plus promising rookies who are benched the entire game (Cameron Payne) and guys you thought retired five years ago (Nazr Mohammed). Even so, entering this 3-6 matchup, the Thunder were considered likely to sweep the Mavericks, who limped into the playoffs after Chandler Parson injured his knee and Zaza Pachulia forgot how to play basketball altogether.

After Oklahoma City massacred Dallas in their first playoff meeting, that narrative seemed on track. But in Monday’s game 2, Stephen Adams’s last-gasp rebound for OKC came seconds too late, and the underdog prevailed. It was the biggest playoff upset in 20 years.

But Adams’s choke wasn’t the only reason the Thunder lost. Kevin Durant was bad. He shot an un-MVP-like 7-for-33 from the field, but that won’t happen again in this series. Russell Westbrook turned into a pumpkin in the last five minutes of the game, historically his one drawback (other than his propensity to attend postgame interviews in lensless glasses). Here’s how Westbrook appears on ESPN’s play-by-play for the last five minutes: missed three, missed layup, turnover out of bounds, defensive rebound, missed three, personal foul, offensive rebound, missed layup. Yikes. And unfortunately for the Thunder, this is something the Mavericks can count on going forward. Westbrook plays in sixth gear for 32 minutes—a wonderful attribute, mind you—but wears down in crunch time.

Still, the Mavericks’ win isn’t entirely due to the shortcomings of the other team. The Mavericks excelled at old-man, YMCA ball all night. Nowitzki’s off-balance fadeaway was in full-effect, and he even busted out one of those pump-fake-and-scoop-under shots that made rec leaguers watching across the nation shed a collective tear of joy. Deron Williams nailed a trio of threes in the first quarter on a gimpy leg. Raymond Felton, famous for possessing the exact same physique as many of the beat writers covering him, looked shockingly fleet of foot as he scored a team-high 21 points. Salah Mejri, a Tunisian seven-footer came off the bench and scored an efficient 12 points on just 7 shots.

And even with all of that, if Adams’s release had been just a touch quicker, this series would’ve been 2-0 and likely over.

Can Dallas win this series? It’s unlikely that Rick Carlisle—as masterfully as he’s manifested a playoff team out of a roster consisting of nothing special—can win three more times against Oklahoma City. Game 5 is Monday night, and if Dirk Nowitzki wants to book his flight to Frankfurt on Tuesday, Vegas says he won’t have to cancel it. But if Durant has another night or two like Monday, or if Westbrook gets in his own head or wears down completely, Dallas has a very, very outside puncher’s chance to push it to six or seven games. And then, who knows? Of course, if the Mavericks advance, they are afforded the indignity of squaring off against the Spurs.