BOSTON -- After three quarters of back-and-forth basketball, the fourth period belonged to Boston.
Isaiah Thomas led the Celtics on a late surge in the final period, scoring 11 of his 24 points as Boston took command of the game and its playoff series with a 108-97 victory over the Chicago Bulls on Wednesday night.
The top-seeded Celtics lead the Eastern Conference first-round series 3-2 and can advance with a win in Game 6 on Friday in Chicago.
The Celtics made up for inconsistent shooting by playing stifling defense in the fourth, outscoring Chicago 29-16 in the period and flustering the Bulls into turnovers, missed shots and two technical fouls down the stretch.
"This whole group remains confident in everybody, from the first guy to the last guy," Thomas, who shot just 1-for-10 from beyond the 3-point arc but was perfect at the free-throw line, going 11-for-11. "One thing about playoff basketball, when the shot's not falling, you've got to figure out a way to win."
The Celtics are in a much better position than they were in after the Bulls came to Boston and won the first two games of the series. Chicago then lost two straight at home.
"We believe in one another. We went to Chicago knowing we were going to win those games, not hoping," said guard Avery Bradley, who also scored 24 for the Celtics. "Now it's our job to continue. Play the same way and finish the series in Chicago."
Boston's Al Horford finished with 21 points, nine assists and seven rebounds. Kelly Olynyk scored 14 points off the bench for the Celtics, who closed the rebounding gap that the Bulls used to win the first two games. Chicago still outrebounded Boston, but the margin was just 42-38, and the Celtics outscored the Bulls in the paint 56-42.
Dwyane Wade had 26 points, 11 rebounds and eight assists for the Bulls, who sputtered down the stretch. Jimmy Butler and Robin Lopez added 14 points apiece for the Bulls, who were without point guard Rajon Rondo (broken thumb).
"When you're in a series like this, small details are very important," Wade said. "They got some things on us that we didn't want to give up in late in the fourth."
Chicago opened the game strong and kept it tight through the first three quarters.
Neither team turned the ball over during a back-and-fourth third quarter. Crowder made four free throws in the final 40 seconds of the period to put Boston up 79-78, but Chicago still had six seconds left and Butler put the Bulls back on top with a 3-pointer at the buzzer.
Chicago was leading 81-79 early in the fourth before Thomas took over. Thomas, who converted a three-point play earlier in the period, hit a layup that put the Celtics back up 86-85 and started Boston on a 19-4 run that secured the first win for a home team in the series.
Olynyk converted a three-point play with 8:09 left, then Horford stole the ball from Lopez at midcourt and went uncontested for a dunk to make it 91-85. Horford followed that up with a three-point play.
The Bulls unraveled as Boston continued building up a bigger lead, sending Thomas to the line after technicals called on Wade with 4:52 left, followed by a technical on Lopez 32 seconds later.
"The emotions run high in the game. Unfortunately we got a few techs at the end," Wade said. "I'd rather see that than see nothing. It shows that people care
Thomas hit both free throws after the technicals along with two from the line in between on the foul that frustrated Wade into the technical. Horford added two free throws to make it 104-89.
Isaiah Canaan got the start in only his second career playoff game and finished with 13 points for the Bulls. Although Canaan started and played well, Wade was running the offense for a majority of the game and said he expects to continue that role in Game 6.
"We're in a good place. It's just weird because we won the first two here and they came and won the next two," Wade said. "It's up to us to win the ballgame and bring it back here."
If the Bulls win Friday, Game 7 is Sunday back in Boston.
NOTES: Chicago G Rajon Rondo traveled with the team and was not wearing a cast or splint on his injured right hand, but he stood out from his teammates in a tan suit. ... Chicago G Isaiah Canaan was inactive the first three games of the series and made his career postseason debut Sunday in Game 4, finishing with 13 points and three assists in 34 minutes. ... Boston fans jeered Bulls C Robin Lopez in the third quarter when he rushed a shot from just inside the foul line and the ball sailed over the backboard. Lopez still scored 10 in the quarter after finishing the first half with only four points and three rebounds.