ATLANTA (AP) — LeBron James scored 31 points, while J.R. Smith made eight 3-pointers and added 28 to lead the Cleveland Cavaliers past the top-seeded Atlanta Hawks 97-89 in Game 1 of the Eastern Conference finals Wednesday night.

Making a tough night even worse for the Hawks, they sustained a potentially huge blow in the fourth quarter when DeMarre Carroll went out with a knee injury.

Intent on bringing Cleveland its first NBA title, James sealed the victory with a soaring dunk in the final minute. But Smith was the one who ignited the Cavaliers, going 8 of 12 from 3-point range.

For the Hawks, it was the second straight series in which they’ve lost the opening game at home. Cleveland will look to take command of the series in Game 2 Friday night.

Jeff Teague led Atlanta with 27 points. Carroll, who had been the Hawks’ leading scorer in the playoffs, went down driving to the basket with 4:59 remaining. He was helped to the locker room, not putting any weight on his left leg. Coach Mike Budenholzer said the initial diagnosis was a sprained knee, with an MRI scheduled for Thursday to determine the seriousness.

The Cavaliers took control when Smith knocked down back-to-back 3s in the third quarter. After the second one, he turned toward the Atlanta fans and blew off his right index finger and motioned toward his side, like he was holstering his pistol.

Yep, he was that hot.

Cleveland outscored the Hawks 22-4 over the final 5 minutes of the third quarter and the first 2 minutes of the fourth. In fact, the Cavs scored the first 11 points of the final period for their biggest lead, 85-67.

Carroll’s injury left the crowd in silence and would be tough for the Hawks to overcome. Not only was he their main defender on James, he has turned into an offensive force in the playoffs, averaging more than 17 points coming into the first Eastern Conference final in Atlanta history.

Even without Carroll, Atlanta closed to 91-87 with about a minute remaining. But James got loose from Paul Millsap out near the arc, took off down the lane uncontested and slammed home a dunk that finished off the Hawks.

Smith has been a huge addition for the Cavaliers since he was acquired in January as part of a three-team trade with New York and Oklahoma City, a player once known for his selfishness learning to work well with within the confines of a team led by James.

When the Cavaliers really needed Smith in Game 1, he seemed to make every shot.

Looking to get off to a quick start in front of their raucous home crowd, the Hawks jumped out to a nine-point lead in the first quarter. Atlanta shot 61 percent and James went to the bench with about 3 minutes remaining in the period after picking up his second foul.

The Cavs hit just 35 percent in the opening quarter, but a dominating performance on the boards kept Atlanta from pulling away. Cleveland outrebounded the Hawks 15-6 over the first 12 minutes, actually yanking down more offensive rebounds (seven) than Atlanta’s total output.

James returned in the second quarter and began to take control of the Cleveland offense. He scored 14 points in the period on 7-of-9 shooting, taking advantage when the Hawks tried to bait him into a third foul by guarding him with smaller players. James kept driving to the basket but managed to avoid a lot of contact.

The game was tied 51-all at the half.

POUNDING THE BOARDS

The Cavaliers finished with a 49-37 rebounding edge, exposing Atlanta’s major weakness during the regular season.

Timofey Mozgov led with 11 rebounds, while Thompson chipped in with 10.

James also had eight rebounds, giving the Cavaliers three players who had more than anyone on the Hawks. Millsap, Kyle Korver and Al Horford each had seven for Atlanta.

TIP-INS

Cavaliers: This was the first time in franchise history that Cleveland won Game 1 of a playoff series on the road. The Cavs had been 0-14. ... Thompson had 14 points, while Mozgov and Iman Shumpert added 10 apiece.

Hawks: Horford had 16 points, Millsap 13 and Kent Bazemore 10, including a massive dunk in the second half. ... Bazemore figures to get even more playing time if Carroll is sidelined. ... Millsap picked up a technical foul midway through the third quarter when he complained about an offensive foul call. Millsap was called for setting an illegal pick as he tried to free up Korver. Actually, though, Millsap was the one who seemed to get bumped. ... Floyd Mayweather Jr. was sitting courtside. When he was shown on the video board, most of the crowd booed.