ATLANTA -- The Atlanta Hawks were going to have trouble slowing down Cleveland Cavaliers forward LeBron James at full strength. It'll only be tougher as the Eastern Conference Finals continue.

James scored 31 points, and guard J.R. Smith came off the bench to hit eight 3-pointers in the Cavaliers' 97-89 win over the Hawks on Wednesday at Philips Arena. But the biggest storyline to come out Game 1 was an injury to Atlanta's versatile forward DeMarre Carroll.

Carroll, an unrestricted free agent this summer and the Hawks' best player so far in the postseason, went down hard on a drive late in the fourth quarter and had to be helped off the court, favoring his left leg. Initial reports were a left knee sprain. He was on crutches after the game and will have an MRI on Thursday. Atlanta was already without defensive stopper Thabo Sefolosha, who was lost for the year in March to knee surgery.

"At the end of the day, the NBA is a brotherhood," said James, who gave Carroll a pat and some encouragement as he was being helped off the floor. "You never want anyone to get injured during combat. That's what went through my mind."

Game 2 is Friday in Atlanta.

James took over in the second quarter of Game 1, using pick-and-rolls to get matched up against smaller defenders. He scored 14 in the second quarter, helping the Cavs erase an early deficit.

"LeBron came in with a purpose tonight," Cleveland first-year coach David Blatt said. "He led his team, as he's known to do in big games."

Smith finished with 28 points, including back-to-back 3s in the third quarter that helped Cleveland break open a close, back-and-forth game.

Point guard Jeff Teague led the Hawks with 27 points, and forward Al Horford added 16 points and grabbed seven rebounds.

"We just got to come out fighting, come out ready to play with a lot of intensity (in Game 2)," Teague said. "It's going to be a war the next couple of games. We know that. So it's a must-win for us next game with our backs against the wall."

Cleveland led 85-69 with 10 minutes left in the fourth quarter before Atlanta mounted its last charge. Hawks guard Kyle Korver hit a corner 3-pointer, and Teague followed with a layup to trim the deficit to 11 and force a Cleveland timeout.

The Hawks closed to 91-87 on a fast-break layup by forward Kent Bazemore with 40 seconds left. But James broke free on Cleveland's ensuing possession and threw down a one-handed dunk to slam the door on Atlanta's comeback hopes.

"Coach drew up a play, and we just executed," James said of the clinching possession.

Smith, who came over from the New York Knicks midway through the season, outscored Atlanta's entire bench 28-19. The 28 points was a playoff career high for Smith, who has had a mercurial career in the NBA.

Cavs point guard Kyrie Irving, who has been battling ankle and knee ailments, started and played 27 minutes. He finished with 10 points and six assists, but wasn't his normal explosive self.

"He was not on a minute restriction," Blatt said of Irving. "But he got banged up a little bit, and we limited his minutes as a result."

The Cavaliers fought off a raucous crowd at Philips Arena that was hosting its first conference finals. They dominated the backboards and stymied the Hawks' offense in the second half. Cleveland used its superior size to outrebound Atlanta 49-36, with center Timofey Mozgov grabbing 11 rebounds and forward Tristan Thompson had 10 boards.

The score was tied 51-51 after a back-and-forth first half. Teague got off to a hot start, scoring 17 in the first 24 minutes. Smith came off the bench for 11 first-half points, including three 3-pointers.

The Cavaliers hit 10 of 26 3-pointers, while Atlanta went 4 of 23 from beyond the 3-point arc.

Atlanta coach Mike Budenholzer said his team needed to be more aggressive offensively moving forward, but also lamented the loss of Carroll.

"DeMarre is a complete player," Budenholzer, the NBA Coach of the Year, said. "He has a big impact on both ends of the court. Other people will have opportunites to make defensive plays, to make offensive plays and that will be a great opportunity and a great challenge."

Bazemore, who finished with 10 points, will likely pick up most of Carroll's minutes, if he can't go.

NOTES: Cleveland PG Kyrie Irving, who left Game 6 of the Cavs' series with the Chicago Bulls with knee and foot injuries, told reporters Wednesday that the six days of rest did him well and he felt good heading into the Eastern Conference finals. Irving is dealing with a right foot sprain and left knee tendinitis. ... Atlanta G Kyle Korver, considered one of the best shooters in the NBA, made only six of 22 shots in the final four games of Hawks' series against the Washington Wizards. ... The Hawks won three of four meetings with the Cavaliers in the regular season. ... Cleveland G Iman Shumpert played college ball at Georgia Tech. ... Boxing champion Floyd Mayweather and hip-artist Ludacris were among the celebrities in attendance.