NBA In-Season Tournament delivers as Pacers upset Celtics in quarterfinals

When NBA commissioner Adam Silver dreamed up the concept for an In-Season Tournament, games like Monday night's battle between the Boston Celtics and the Indiana Pacers was no doubt exactly what he had in mind. In years past, a weeknight fall matchup between these two teams would have been ignored by everyone other than Celtics and Pacers diehards. Instead, a national audience was treated to electric back-and-forth and what might have been the most intense December NBA game in years.

In the end, it was the Pacers who walked off their home floor of Gainbridge Fieldhouse with the victory in this first-ever elimination round of the inaugural In-Season Tournament, a 122-112 win over the Celtics. They'll now head to Las Vegas where they will face the winner of Tuesday night's Eastern Conference semifinal between the New York Knicks and Milwaukee Bucks.

Tyrese Haliburton led the way for the Pacers, with a 26-point, 13-assists, 10-rebound triple double. Incredibly, he didn't turn the ball over a single time. The Pacers, who own the league's most potent offense, and this season have scored at a record rate, drilled 19 of their 40 looks from deep.

The game turned in the second half. First, Haliburon — playing in his first ever TNT game — came out attacking and looking for his own shot.

But also, after allowing the Celtics to run lay-up lines in the first half, they tightened up on defense, just enough so that their explosive offense could take them home. Seven different Pacers players finished the night with double-figure scoring marks.

Jayson Tatum (32 points, 12 rebounds, six assists) and Jaylen Brown (30 points and nine rebounds) led the way for Boston. But the Celtics badly missed the backline defense and size of Kristaps Porzingis, who missed his fourth straight game with a calf strain.

The final few minutes of the fourth quarter felt like a playoff game. It featured multiple lead changes, a raucous crowd and big-time shots, most notably this pull-up triple from Haliburton with 1:33 left in the game to break a 105-105 tie, which he drilled while being fouled. 

It was a brilliant play capping off a thrilling night. Silver and the NBA deserve credit. The game was everything they told us the In-Season Tournament could be.

Yaron Weitzman is an NBA writer for FOX Sports and the author of Tanking to the Top: The Philadelphia 76ers and the Most Audacious Process in the History of Professional Sports. Follow him on Twitter @YaronWeitzman.