BOSTON — It was only the second quarter, but the Celtics’ Jayson Tatum seemed determined to build on a theme as he eyed an opportunity on Wednesday night. He took a hard dribble at Stephen Curry, spun to his right and drove straight into the lane before depositing a layup over his smaller defender.

The Celtics were eager to familiarize themselves with the basket in Game 3 of the N.B.A. finals. So they used their size to bully various members of the Golden State Warriors in the low post and off the dribble. They attempted layups. They dunked. They threw short jumpers off the glass.

In the process, Boston even survived one of Golden State’s hallmark third-quarter runs to escape with a 116-100 win at TD Garden and take a 2-1 lead in the series. Game 4 is in Boston on Friday.

The Celtics, who opened the fourth quarter by building a healthy cushion, were led by Jaylen Brown, who had 27 points and 9 rebounds. Tatum added 26 points, 9 assists and 6 rebounds, and Marcus Smart finished with 24 points. Curry had 31 points in the loss, and Klay Thompson added 25. The Celtics did most of their damage in the paint, where they outscored Golden State, 52-26.

After the first two games were in San Francisco, the series swung to Boston, a fitting site for the finals as the league celebrates the last few flickering embers of its 75th anniversary. The Celtics are chasing their 18th championship, while Golden State is making its sixth finals appearance in eight seasons.

Two of the league’s original franchises, the Celtics and the Warriors now mirror each other in another important way: Both rosters were largely constructed through drafting. And while Boston is making its first finals appearance since 2010, Celtics Coach Ime Udoka said he hoped to emulate Golden State’s long-term success.

“It’s a model for what we want to do here,” Udoka said.

The Celtics, who lost Game 2 on Sunday, have not lost consecutive games this postseason. Before Wednesday’s game, Udoka cited his team’s resilience.

“I think we put it behind us pretty quickly,” he said, “and kind of attacked the areas that we did poorly and tried to improve on those.”

About an hour and a half before the start of Game 3, as some of Golden State’s players made their way onto the court for individual warm-up work, the reserve guard Gary Payton II noticed that one of the rims seemed a bit off. He was right: It was about two inches too high.

“It happens every once in a while,” Golden State Coach Steve Kerr said before the game. “Players have a really sharp eye for that.”

The rim was soon lowered to its proper 10-foot height, but it did not seem to help. Golden State got off to a brutal start, missing 11 of its first 15 field-goal attempts as Boston ran out to a 24-9 lead. Making matters worse, Curry picked up two early fouls.

If there was concern for the Celtics, it came in the form of Tatum’s right shoulder, which he first injured in the Eastern Conference finals against Miami. On Wednesday, he was grimacing in pain after drawing a foul on an early drive.

But his 3-pointer midway through the second quarter pushed the Celtics ahead by 18. Boston shot 57.4 percent from the field to take a 68-56 lead at halftime.

All eyes, though, were on the start of the second half. In Games 1 and 2, Golden State had dominated both third quarters, outscoring Boston by a total of 35 points. The third quarter was particularly problematic for the Celtics in Game 2, when they shot 4 of 17 from the field, committed five turnovers and were outscored, 35-14. A close game quickly turned into a rout.

On Wednesday, Golden State was trailing by 9 when the team summoned some more third-quarter magic. Curry made a 3-pointer and absorbed contact for good measure when the Celtics’ Al Horford slid underneath him. It was ruled a flagrant-1 foul, which meant Golden State would retain possession after a free throw.

Curry sank the free throw, then Otto Porter Jr. buried another 3-pointer for a 7-point possession that trimmed Boston’s lead to 2.

It was an anxious moment for the Celtics, who could have folded but instead revealed their toughness once more. Early in the fourth quarter, Smart banked in a 3-pointer. Moments later, Grant Williams corralled an offensive rebound for a put back, forcing Kerr to a call for a timeout as the home crowd roared.