BOSTON — JJ Redick opened Game 2 with a corner three-pointer, a foreshadowing moment for the shootout that would become the rest of the night.

Redick, who finished with a team-high 23 points, scored the next five Sixers points before the Celtics even had a chance to get on the board, another indication of what the rest of the night would look like.

The Celtics and the Sixers traded three-point flurries and runs before the Celtics came out on top with a 108-103 win to take a 2-0 lead in the Eastern Conference semifinal.

"You just have to account for Redick every minute that he's in," Celtics coach Brad Stevens said. "You have to account for [Robert] Covington the way he was shooting the ball, obviously [Marco] Belinelli hit some big shots. All those guys are more than capable."

The rest of the Sixers followed Redick's lead and jumped out to an impressive 22-point lead midway through the second quarter. That  included Redick, Covington, and Dario Saric shooting 7 of 10 from beyond the arc.

The Celtics weren't going to just lie down, though and the Sixers knew it.

"The notion that we were going to maintain a 20-point lead and walk out of the Boston Garden wasn't on my mind," Sixers coach Brett Brown said.

He was right, the Celtics had their own arsenal of threes to unleash. Boston closed the first half on a 25-8 run that included treys from Marcus Smart, Terry Rozier, and Jaylen Brown, who returned from a hamstring injury and finished with 13 points off the bench.

"We give them credit where they found open three-point shooters," Brown said of the Celtics' surge at the end of the second quarter.

In Game 1 on Monday night, the Sixers were atrocious on defense and shot just 5 of 26 from three-point land, definitely not a recipe for victory.

"What you saw the other night was not the Philadelphia 76ers," Brown said shortly before Game 2.

His team backed up the coach's words on most fronts, playing with a higher intensity on defense and moving the ball in a way that continued to open up shooters. But the Celtics were doing the same thing on their end and were ready for a fight.

"By that time you're just happy to be in a back-and-forth game," Stevens said.

The second half of the game included seven lead changes, five ties, and 14 more three-pointers combined from both teams.

Rozier and Smart combined to go 8 of 19 from deep. Smart, who did not hit a three-pointer in the three games he played during the Celtics' first-round series against the Bucks, has now hit six from beyond the arc against the Sixers.

"He may miss some throughout the course of the season," Stevens said of Smart's three-point shooting. "But when these lights are on and he steps up into that shot, I believe in him."

The NBA is often called a game of runs and Game 2 between the Sixers and the Celtics was exactly that, with huge plays and three-pointers flying from every direction.

The Sixers opened the game on that 8-0 run with two threes from Redick. The Sixers missed four threes in the final minutes and the Celtics held on to take the win.