CHICAGO — Isaiah Thomas is back and so are the Boston Celtics.

After a couple games of minimal offensive contribution, Thomas and Jimmy Butler had a battle to define the series, and the Celtics came out on top with a 104-95 win.

Thomas finished with 33 points, 7 assists and 4 rebounds, working the 1-5 high pick and roll with Al Horford to perfection in the second half.

The Bulls made their run in the third quarter, as is tradition, taking their first lead of the game at 65-63 with 4:35 left in the quarter. Boston responded with a 12-0 run and maintained a comfortable distance the rest of the way, hovering around 10 points.

Thomas took the initiative, working the high screens to get Robin Lopez out to the three-point line and blow him away. Jimmy Butler tried to stop Thomas, but not even he could contain Thomas’s explosiveness Sunday.

The Bulls tried to hang in while Thomas went on his run, but the Celtics finally were effective in transition. Al Horford was a huge factor in both creating and finishing, as the Celtics won the fast-break battle 17-9 thanks to plays like this.

This was the final hurdle on the court for Thomas, who finally had a complete performance in a win since his sister Chyna’s passing.

“I can’t believe it,” coach Brad Stevens said. “But what he’s been through and the day-to-day, it’s been unfathomable the way that he’s performed on the court.”

He had excelled in Game 1, propelled by the numbness as much as the raw adrenaline of being 24 hours from his sister’s death. Games 2 and 3 were a bit of a lull for Thomas, who admitted Sunday that he still isn’t checked in emotionally.

But Game 4 was the big turnaround, which couldn’t have happened without the vital support of his entire organization.

“I mean, they’ve been everything,” Thomas said. “This organization is the best organization there is, from the people who work in the Garden to the players, the coaches, everybody who’s a part of the Celtics. They’ve been supportive. The whole world has, really, so I can’t say enough about that.”

HOT CHOCOLATE GETTING CRUNK

Gerald Green followed up his breakout game with a truly delectable performance, scoring 16 points in the first half with 5 rebounds. The Bulls were in trouble when Rajon Rondo went down, but they haven’t even come close to finding an answer for Green and the more dynamic Celtics offense.

“I’ve said it all along: He’s going to win us a playoff game and I really believe that. We have so much confidence in him and I know when he’s on the court, he spaces the floor, not just for myself, but for everybody, even if he’s not making shots.”

Green was solid in Game 3, but was head hunting in Game 4. Stevens has always said that Green is known around the league as ready to explode at any moment. That moment has finally come after countless games watching from the end of the bench. It’s been a big part of why Thomas feels he has more of a chance to attack the rim.

“I love when (Gerald’s) out there because he gives me space to go to work and also another outlet when I get in trouble because I know he can knock down those shots.”

Green said before Game 4 that he was trying to geek out on the court and just be crunk. He brought the party to United Center Sunday.

“I’m just trying to bring a lot of energy,” Green said. “It’s easy playing with Al Horford and Isaiah Thomas , man. Those guys are great orchestrators of offense.”

The Celtics head back to Boston with home court advantage restored. Now it’s time to party at home.