The Boston Celtics and Indiana Pacers have gone on a wild ride together this season. Facing off for an In-Season Tournament-augmented five regular season matchups, they’ve traded blows exceptionally often across the first half of the season. The teams entered their fifth and final matchup of the regular season looking to break a 2-2 tie on the year, a slate that has been hotly contested outside of a blowout win in November for the Celtics. In the end, it was the Celtics who got the last laugh, recording a 129-124 win at TD Garden to claim the season series.

This fifth game was a little different than the rest. The Celtics got their first look at an old foe in a new environment tonight, as they faced off with Siakam for the first time as a Pacer — just his seventh game for the team. While Siakam has been settling in to his new digs, one wrinkle of note has been how he’s had to do it without the services of his co-star. Tyrese Haliburton returned to the Indiana lineup tonight, having been inactive for the Pacers’ last five games, and 10 of their last 11. This was just the duo’s second game together, though it was short-lived — Haliburton recorded just 22 minutes as the Pacers approached his return to play with extreme caution.

The starting five carried the bulk of the load tonight. All five starters scored at least 17 points on the evening, compared to just 16 combined for the bench. Leading the way was Jayson Tatum, who scored a hyper-efficient 30 points (12-of-19 shooting) while grabbing seven rebounds and dishing seven assists. Jaylen Brown added 25 of his own, while Jrue Holiday scored 17 on 6-of-8 shooting and Kristaps Porzingis recorded a 17-point, 12-rebound double-double.

After starting off slowly against the Clippers and Pelicans, the Boston offense looked more lively as play began this evening. Each member of the starting lineup found his way onto the scoreboard, and only Holiday connected on fewer than two buckets. The Celtics were going to need every point tonight, facing an explosive Pacers offense with its beating heart, Haliburton, back on the court. But Indiana shot just 36.7% compared to Boston’s 53.3% in the first quarter, and the Celtics took a 36-26 lead into the second quarter.

Nobody started out quicker this evening than White, who appears to have fully broken out of a January slump that has seen him shoot just 38% from the field for the month. White was crucial down the stretch of Monday’s win over the Pelicans, making plays on both ends of the floor in crunch time to secure the win, and that high level of play carried over to this game. He scored 24 points on 8-of-16 shooting for the night, and recorded a crucial block on a corner three-point attempt to help secure the game for Boston. Not a bad way to break a slump.

Though Al Horford (neck/rest) and Luke Kornet (hamstring) missed the game, the Celtics enjoyed an increasingly rare opportunity to deploy their default starting lineup. Those starters took a buzzsaw to the Indiana defense. Even as the Pacers’ offense found a bit of momentum, they still wound up buried under a mountain of Celtic points. Led by 23 from Tatum and double-digit scoring from four of their starters (Holiday scored eight), the Celtics followed their 36-point first quarter with 45 in the second, and took a comical 81-66 lead into the halftime break.

Quietly, the first half ended on a bit of a sour note for the Celtics. It’s odd to say about a team that scored 81 points in a half, but Boston seemed to lose their edge just a bit in the closing minutes. A buzzer-beating heave from Haliburton found the bottom of the net, sucking a bit of the air out of the room for the Celtics’ offense.

That negative momentum carried over to the third quarter, where, unbelievably, the Celtics found their lead cut to single digits as the Indiana run stretched to 16-4. Rebounding was a substantial culprit here, possibly suggesting tired legs on the part of Boston. The Pacers piled up an unacceptable 19 offensive rebounds on the night, deflating the Celtics’ defense by finding a number of second-chance scoring opportunities. Boston’s lead dwindled down to just three points by the eight-minute mark.

The Celtics course-corrected slightly as the returned from a Joe Mazzulla timeout, in part due to some heady play from Brown. The Pacers were still able to complete the comeback. The tied the game up at 91 apiece with just over five minutes to play in the third, and briefly took the lead moments later at 94-93. The Celtics received a boon in the ensuing minutes, though, as Haliburton hit his minutes cap in his return from injury and found himself resigned to the bench for the remainder of the contest. Absent their offensive engine, the Indiana offense faltered ever so slightly, and the Celtics were able to take a three-point lead into the final quarter, 106-103.

Tonight, the fourth quarter was going to be a matter of stamina. Staring down their second tightly contested game against a likely playoff team in as many nights, the Celtics were going to have to earn another win just like Mazzulla asked for the night before. Nothing had come easy since the midway point of the second quarter, and that didn’t look likely to change in the fourth.

As the final frame began, the Celtics pounced early. Apart from a mental mistake by Neemias Queta on a jump ball, they played sharply and recorded a quick 9-3 run to push back ahead by nine points. The lead stretched back into the double-digits after a timeout, the Celtics firmly placing themselves in the driver’s seat. The lead would remain around nine points for the next several minutes of play.

The final two minutes of the game saw an Indiana rally. The Pacers capitalized on mental mistakes by the Celtics to go on a quick 6-0 run and abruptly draw back within three points with just over a minute remaining. Given a pair of crucial chances to close the gap, though, the Pacers found themselves stymied by the Boston defense twice in a row. White blocked a corner three, and Tatum blocked a layup after the Pacers retained possession, and the Celtics finally shut the door on Indiana for the regular season.

Next up, the Celtics will conclude their season series with a Los Angeles Lakers team in an increasing state of disarray, on the TD Garden floor this Thursday at 7:30 EST on TNT.