(CBS) Bulls forward Bobby Portis has been suspended eight games for punching teammate Nikola Mirotic in practice Tuesday.

Portis’ punch came after the two engaged in an altercation that involved shoving, and the blow landed Mirotic in the hospital with two broken bones in his face and a concussion. Mirotic is expected to be out four to six weeks, Bulls executive vice president of basketball operations John Paxson said. He will need to clear the concussion protocol before returning.

“Both players owned responsibility in the incident itself, but only one player threw a punch,” Paxson said Wednesday at the Advocate Center. “That punch connected, and for us, that is inexcusable. It’s not who we are. It disappoints us in terms of what happened.

“Bobby Portis is not a bad person. He’s a good kid, he’s a competitive kid. But in this incident, he made a mistake. We all know when you make mistakes, we got to suffer the consequences. The consequences in this situation are the eight games that he will not be with us.

“There’s altercations a lot of times, but the result of Niko’s injuries are why we’ve taken the position that we have.”

Tthe Bulls got counsel from the league on how to handle the situation, Paxson said. Portis will be allowed to practice with the Bulls during his suspension. He was instructed to stay home Wednesday, and the plan is for him to return to the team Friday, a day after Chicago opens its season at Toronto on Thursday night.

It’s unclear if Portis plans to appeal his eight-game suspension.

“Our responsibility now is to be supportive of both Niko and Bobby,” Paxson said. “We’re a team. We’re a group. You have to proceed that way. These types of things do happen. I’ve been a part of them. I’ve seen them.”

Portis is one of four healthy Bulls big men, but they’ll only have three at those positions for the first eight games. Rookie Lauri Markkanen will start in place of Mirotic, coach Fred Hoiberg said.

“My job is to not let this moment derail us,” Hoiberg said. “My job is to get these guys prepared to go out and fight and play as a group, and I’m confident our guys will do that.”

Mirotic, 26, had won the Bulls’ starting power forward for the season opener Thursday. He averaged 10.6 points and 5.5 rebounds in 24.0 minutes last season.

Portis, 22, was battling for backup minutes. A first-round pick in 2015, he averaged 6.8 points and 4.6 rebounds in 15.6 minutes last season.