The only real opponent the Celtics have in this series is themselves

Al Horford beat the Pacers defense to score 2 of his 10 points.Barry Chin/Globe Staff/Globe Staff

In the storied hoops history of the Boston Celtics there have been a lot of unforgettable, goose-bump-inducing playoff games. The dual playoff debut of Kyrie Irving and Gordon Hayward wasn’t one of them. This wasn’t one for the scrapbook. It was one for the scrap heap.

The Parishioners of the Parquet needed to avert their eyes as the Celtics and Indiana Pacers swapped halves of horrid “offense.”

The 49-win, No. 4 seed Celtics embarked on their playoff journey Sunday after a season of disappointment and division. Was it the beginning of something special or the beginning of the end of the Kyrie era? Either way, this tractor-pull on the parquet will be a forgettable footnote.

The Celtics slogged their way to an 84-74 victory over the Pacers in Game 1 of their Eastern Conference first-round series at TD Garden. Celtics coach Brad Stevens said the game harkened back to 1980s playoff basketball. There was definitely an eighties vibe, as in the first team to 80 wins.

Game 1 wasn’t riveting, but it was revealing. Here’s the reality of this series: due to offensive talent disparity the Pacers can’t beat the Celtics in this series. The Celtics can only beat themselves. They’ve been happy to oblige this season, losing games they shouldn’t to teams they shouldn’t, so it can’t be ruled out. Boston engaged in hoops self-harm in the first half, shooting 32.5 percent from the floor and turning the ball over nine times.

The unsolved mystery of the Celtics’ season is why they are unable to play to their talent level. Due to Indiana’s talent level, they don’t have to in this series. The Pacers will scratch and claw. But without injured All-Star Victor Oladipo, they’re like the little brother facing his big brother in backyard hoops — they’re playing at a serious disadvantage. If the playoffs really do represent a reset for the Celtics, then they should squeeze the life out of a lesser opponent like a python smothering its prey.

This was a game played at the Pacers pace and on their terms. They limited the Celtics to just 28 of 77 shooting (36.4 percent), forced 17 turnovers, and kept Playoff Kyrie contained. What has to be disheartening for the Indiana is none of it mattered. The Celtics still led by as many as 22 in the fourth quarter.

With these Celtics, the focus is always on the big picture. It’s about realizing their potential as a championship contender. So, Stevens was practically giddy that his team had to grind out a game where its offense left a lot to be desired, and defense and desire carried the day and a double-digit win.

“That’s maybe the best combination for our team,” said Stevens. “It was hard. It wasn’t pretty. Things went against us, even a couple of bounces went against us in the first half where they picked it up and hit end of shot-clock plays or putbacks.

“You got to stay together, and you got to grind it out. There will be games where we make a lot of shots. It will make us look better than we played. Today, we played a little better than we looked.”

At least someone enjoyed this contest.

The Celtics displayed a playoff stage fright at the outset. The fresh start they’ve been promoting was replaced by a slow start. They fumbled the ball and couldn’t find the range from 3-point land, falling behind, 45-38.

“We know offensively that probably was the worst half that we played all season,” said Irving.

Against a team that could, you know, score, they would have been down double-digits. Instead, they got a reprieve. Then Indiana decided to be complicit in its own demise with a third quarter of offensive basketball so feckless it should have come replete with peach baskets.

Scoring became a Sisyphean feat for the Pacers. They played like the basket was booby-trapped. The Pacers didn’t score a point until there was 7:02 left in the third. They missed their first 11 shots from the field and didn’t register a make until Cory Joseph’s finger roll with 3:28 left in the quarter cut Boston’s advantage to 60-50.

Coach Nate McMillan’s gang that couldn’t shoot straight finished the quarter 2 of 19 and scored 8 points, EIGHT. Irving, just 3 of 10 for 7 points in the first half, equaled Indiana’s third-quarter output on his own on his way to a pedestrian 20-point evening.

For good measure, the Pacers reciprocated the Celtics’ first-half charity with five turnovers, matching Indiana’s entire first-half total.

The Celtics’ elevated defensive intensity played a part in the Pacers’ futility. Credit them. But it was mostly Indiana’s offensive ineptitude in the absence of Oladipo, something that has plagued the plucky Pacers since Oladipo went down Jan. 23 with a ruptured quad tendon. Pulling Celtics legend and former Pacers team president Larry Bird out of the Garden stands to sink a shot had to cross McMillan’s mind as he watched his team shoot 33 percent.

“We just didn’t make enough shots,” said Pacers forward Thaddeus Young. “We had a lot of good looks in that third where we were coming down in transition and were getting wide-open looks. They were rattling in and out. We just missed shots. As a team, you hate to see those not go down. I think we did a fairly good job of going out there and playing defense. I think the biggest factor that killed us in that game was that third quarter.”

The Pacers’ plight was summed up with 11:15 left in the fourth quarter when Joseph, who led them with 14 points, airballed an open floater. Jayson Tatum came down the other end and sank a silky, one-on-one, pull-up J.

The ball doesn’t lie. The Celtics possess players who can score individually with ease. The Pacers decidedly do not. That was the difference. That was the game. That’s going to be the series.

The Celtics held serve in Game 1, beating Indiana for the third time in 16 days. The biggest threat to them in this series is complacency and boredom. The Pacers are a relentless group that squeezes every ounce of talent out of the tube. They’re the anti-Celtics in that regard.

If the Celtics could play with the cohesion, commitment, and execution of the scrappy Pacers they would be the East Coast answer to the Golden State Warriors that we expected.

The Pacers are the perfect foil for the Celtics. They can push them, prod them, and poke them. But they can’t really harm their playoff hopes.

If the Celtics lose this series, they have no one to blame but themselves.