CHICAGO — Isaiah Thomas is playing through tears after the death of his sister, drawing strength from the rest of the Boston Celtics.

They found another gear in Chicago.

Thomas scored 33 points, and the Celtics beat the Bulls 104-95 on Sunday to tie their first-round playoff series at 2-all.

"Mentally and emotionally, I'm not here so I just feed off what the guys give me," Thomas said. "They give me a lot of confidence. I can't do it without those guys. They believe in me and being here is what makes me feel sane and somewhat normal through these tough times."

Thomas' life changed just over a week ago when his younger sister Chyna was killed in a one-car crash in their home state of Washington. He spent time with his family in Tacoma between games in Boston and Chicago.

With Game 4 at a critical juncture, the All-Star guard provided a huge lift for a team that has been supporting him in the toughest of times.

Thomas keyed a third-quarter run after the Bulls wiped out a 20-point deficit and briefly went ahead, helping top-seeded Boston return the favour in Chicago after dropping the first two games at home.

Gerald Green made four 3-pointers on his way to 18 points. Al Horford added 15 points and 12 rebounds, and the Celtics pulled even in a series that was in danger of becoming a rout. Game 5 is Wednesday in Boston.

Jimmy Butler carried the Bulls with 33 points and nine assists. Nikola Mirotic and seldom-used Isaiah Canaan each scored 13 points, but Dwyane Wade finished with just 11.

Canaan made his first appearance since April 10, with Bulls coach Fred Hoiberg searching for help at point guard with Rajon Rondo missing his second straight game because of a broken right thumb.

"Just like last game, we were using a lot of energy just to come back," Wade said. "Better starts here at home could've did us a little justice. I thought they did a great job of sticking with their game plan, making tough shots offensively."

The Celtics led by 20 in the second quarter and were still up 10 in the third when Chicago scored 12 straight. The Bulls went ahead 65-63 on Robin Lopez's hook shot with 4:35 left in the quarter.

Thomas answered with back-to-back layups and scored 10 points in a 12-0 run that gave the Celtics a 75-65 lead, and they withstood a push by the Bulls early in the fourth.

CARRY ON

Hoiberg praised Thomas as an "unbelievable competitor" and a "warrior." But he also insisted the guard is getting away with carrying the ball.

"When you're allowed to discontinue your dribble on every possession he's impossible to guard," Hoiberg said. "When you're able to put your hand underneath the ball and take two or three steps and put it back down, it's impossible to guard him in those situations."

Thomas agreed he is just about impossible to defend, saying "not one man can guard me." For that, he credited his teammates and coaches for putting him in position to succeed.

As for Hoiberg's comment?

"That's not the reason why I'm impossible to cover," Thomas said. "I've been dribbling that way my whole life."

GETTING HEATED

The Celtics led 41-21 early in the second quarter. But the game started to turn after Canaan stole the ball from Marcus Smart and scored on a layup.

Smart feigned throwing the ball at Butler. The two came nose to nose, resulting in technical fouls for both players, and the Bulls started to shoot their way back into it.

"He's a great actor, acting tough," Butler said. "That's what he does but I don't think he's about that. I'm the wrong guy to get in my face. Take it somewhere else."

He added: "That's the first time, the last time too. We're not gonna sit here and get in each other's faces, he's not about that life."

RONDO FINED

The NBA fined Rondo for attempting to trip Boston Celtics forward Jae Crowder from the bench in Game 3. Crowder jawed at the Bulls' bench after hitting a jumper and Rondo extended his leg as Crowder walked by him.

TIP-INS

Celtics: Thomas was just 1 of 9 on 3-pointers but made 12 of 13 free throws.

Bulls: Butler made 19 of 23 foul shots after failing to get to the line in Game 3. ... Chicago was just 5 of 24 on 3-pointers even though Canaan — inactive for the first three games — nailed 3 of 7.