(CBS) — Bulls forward Nikola Mirotic has suffered a concussion and maxillary fractures and will likely need surgery after a physical altercation with teammate Bobby Portis in practice Tuesday, the team said.

Mirotic and Portis got in a shoving altercation, which then ended with Portis hitting Mirotic in the face, as Shams Charania of Yahoo Sports first reported. It was a “cheap shot,” according to multiple reports.

The Bulls are still evaluating disciplinary action. Mirotic is out indefinitely, and he’s expected to miss at least several weeks, the Tribune’s K.C. Johnson reported.

Mirotic, 26, was in line to be the Bulls’ starting power forward in 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.

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