CHICAGO _ Bulls respected the Celtics as the No. 1 seed but never feared them.
That showed in Sunday's Game 1.
Jimmy Butler scored 23 of his 30 points in the second half and Bobby Portis and Robin Lopez helped contribute to a massive, 53-36 rebounding advantage as the Bulls prevailed 106-102 at TD Garden.
Game 2 is here Tuesday night.
Butler's two free throws with 3.3 seconds left iced matters after a nervous final minute by the Bulls.
The Bulls missed their first 11 3-point shots but rallied to make 7 of their last 14. That included three from Portis, who finished with 19 points and nine rebounds.
Lopez added a double-double of 14 points and 11 rebounds.
Celtics' Isaiah Thomas scored 33 points, choosing to play the day after his sister died in a one-car accident in his native Washington.
"He's really hurting," Celtics coach Brad Stevens said.
Coach Fred Hoiberg and Dwyane Wade both expressed heartfelt condolences to Thomas and his family.
"All of our hearts go out to Isaiah and his family at this time," Wade said. "We compete against each other but it is a brotherhood. I'm sure everyone will have their moment to say something to him. As competitors, we understand that whenever something is going wrong in our life the best place to be is on this basketball court for those two, two-and-a-half hours. That's where his mind is going to be the clearest."
