The Celtics made a huge comeback Monday night at TD Garden, overcoming a 20-point deficit to beat the Indiana Pacers 103-95.

Boston relied on its bench to fuel the comeback, improving to 18-11 overall. Indiana dropped to 6-23 as their season from hell continues.

The Pacers had the NBA's worst offensive rating and three-point shooting percentage entering the night, but none of that mattered early.

Indiana blitzed the Celtics from deep in the first half, making 12 of 20 threes on their way to a 61-43 halftime lead. Boston looked lifeless on defense. They could not stop Indiana's ball movement, nor could they cool the Pacers’ hot shooting.

That all changed midway through the third quarter.

After another backbreaking Indiana rebound, head coach Joe Mazzulla benched his starters - Jaylen Brown, Derrick White, Payton Pritchard, and Neemias Queta - and subbed in a hungry reserve group that quickly changed the game's tone.

From that pivotal moment, the Celtics took control.

Boston outscored Indiana 60-34 in the second half, flipping the game with energy, effort, and physicality. While Brown led the Celtics with 31 points and 9 rebounds - including 14 in the fourth quarter - the bench truly owned Monday night.

Here are five takeaways from the Celtics’ comeback win over Indiana:

1. Mazzulla The Maestro:

Down 20 and going nowhere, Mazzulla made the boldest move of the night - and maybe the season thus far - by benching his starters.

The message was unmistakable: what was happening wasn’t good enough.

The reserve group of Anfernee Simons, Baylor Scheierman, Sam Hauser, and Luka Garza, with Hugo Gonzalez staying on the floor, responded immediately.

They ripped off a 19-5 run, outworked Indiana on both ends, and injected life into a building that had been flat all night. It wasn’t pretty basketball, but it was effective, and it completely flipped the game.

2. It’s Hugo’s World, We’re All Just Living In It:

Gonzalez continues to look impossible to take off the floor.

The rookie played a career-high 37 minutes, finishing with 6 points, 11 rebounds, and 2 blocks while posting a team-best plus-23.

He opened the second half with the starters, stayed on during the bench takeover, and didn’t come out until the final minute.

His motor, rebounding, and defensive activity stood out all night, and it’s becoming increasingly clear that Mazzulla trusts him in any lineup configuration. Which should surprise no one with the way he plays the game.

A great stat from my friend Sean Grande on the type of season Gonzalez is having amidst a group of super talented rookies:

3. A Tale of Two Shooting Halves:

Indiana couldn’t miss in the first half, hitting 60% of its threes despite ranking last in the league in three-point shooting and offensive efficiency.

Regression hit hard after halftime. Indiana went 1 for 20 from deep, and their offense collapsed.

Boston took advantage and controlled the pace as the comeback grew.

With Boston being the type of shooting team that it is, this type of comeback against a bad team isn’t exactly a shock. But with this type of comeback coming on the back of a performance by their bench unit no one will soon forget, you have to tip your cap to the coaching staff for developing their depth to a level where they’re capable of that type of output.

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4. Garza’s Physicality Mattered:

I did not have Garza getting a shoutout in the takeaways twice in a calendar week this season on my bingo card, but that’s just the type of season this Celtics team is having.

Luka Garza made the most of another opportunity, providing toughness and effort that the Celtics desperately needed.

He finished with 6 points, 9 rebounds (5 offensive), and 3 assists while playing 16 straight minutes in the second half.

While his defensive limitations remain, Garza’s rebounding and physical presence were major factors in swinging the momentum. He was a key piece of the bench unit that turned the game around.

5. Interesting Comments From Jaylen Postgame:

Presented without comment:

Looking ahead, Boston gets a quick rematch with Indiana on Friday night, this time on the road.

If Monday proved anything, it’s that effort - and the right lineup tweaks - can completely change the course of a game.

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Tom Carroll is a contributor for Roundtable, with boots-on-the-ground coverage of all things Boston sports. He's a senior digital content producer for WEEI.com, and a native of Lincoln, RI.