CHICAGO -- Not that long ago, Nikola Mirotic and Bobby Portis couldn't even share the same practice space. Now, the pair has helped spark the Chicago Bulls' three-game winning streak.

Mirotic scored 24 points in his first start of the season, and Portis scored a career-high 23 as the Bulls beat the Boston Celtics 108-85 on Monday night.

The Bulls (6-20) haven't lost since Mirotic made his season debut on Friday after missing 23 games with facial fractures and a concussion sustained in a fight with Portis in practice in October.

Now, it is Mirotic and Portis that are helping the rebuilding Bulls jell on the floor after snapping a 10-game losing streak with an overtime victory over the Charlotte Hornets.

"So far, we have had great chemistry on the team," Mirotic said. "Bobby and I, we are playing good, we are finding each other and we are bringing that energy that the team needs."

Bulls coach Fred Hoiberg, for one, isn't surprised to see Mirotic and Portis playing well together despite their obvious differences that resulted Portis breaking two bones in Mirotic's face during the fight that caused early drama, which included Mirotic refusing to speak to Portis.

"They're both pros," Hoiberg said. "They're both guys that are going to go out and play with great passion and emotion. You can see it with the way they're playing off of each other out there. I love to see the way they're playing together. Hopefully, they'll keep it going."

David Nwaba finished with 13 points for Chicago, which has not lost since snapping a 10-game losing streak on Friday with an overtime victory over the Charlotte Hornets. Kris Dunn added 12 points for the Bulls (6-20) as the Bulls got 55 points from their bench.

Portis, who was suspended for the first eight games of the season following with the altercation with Mirotic, led the effort among his fellow reserves.

"Everybody is of one accord, everybody is playing together and the ball is moving tremendously well," Portis said.

After coming off the bench in his first two games, Mirotic started in the place of Bulls rookie Lauri Markkanen, who missed the game because of back spasms. Mirotic and Portis helped spark a 24-2 second-quarter scoring surge when the Bulls turned a four-point deficit into an 18-point lead

The Celtics (23-6) played without Kyrie Irving, who sat out due to a left quadriceps contusion, and never got closer than 11 points.

"Sometimes, you get your butt kicked -- it's as simple as that," Celtics coach Brad Stevens said. "Chicago dictated the whole game, they played harder than we did, they played with more presence than we did, they played more competitive than we did, they played with more authority than we did. You're not going to win very many games when you play like that."

With Irving in street clothes, Al Horford scored 15 points, and Jaylen Brown, Marcus Smart and Terry Rozier each contributed 13 points for Boston, which was coming off a win at Detroit on Sunday. Aron Baynes finished with 10 points for the Celtics.

Stevens said the Celtics failed to defend Mirotic and Portis like they needed and allowed the Bulls to get to the rim too easily. The result, he said, was predictable as the Bulls led by as many as 30 before winning by 23.

"What do they say -- it was a collective success for them and a collective failure for us," Stevens said.

Defensively, the Bulls kept the Celtics to a season-low 85 points, including just 13 in the second quarter. But now, after stringing together three straight wins in the last four days, the Bulls know they can't allow their recent success to keep them from continuing to improve.

"We've been in a slump the last two or three weeks and now, we've got three wins in a week," Portis said. "That's been big with our team. It's always fun to win."

NOTES: G Kyrie Irving scored 16 points in Boston's victory over Detroit on Sunday, but he took a knee to his quad in that game and experienced discomfort on Monday morning. ... Celtics F Marcus Morris missed his second straight game with a left knee injury. Coach Brad Stevens said the injury would be re-evaluated on Tuesday in Boston. ... Celtics F Al Horford, who had a knee-to-knee collision with another player Sunday, started Monday despite being classified as questionable. ... Bulls F Lauri Markkanen experienced some back issues over the summer and underwent treatment for tightness in his back after the shootaround Monday. Coach Fred Hoiberg said he hopes to get Markkanen back in the lineup soon.