New York Jets quarterback Geno Smith had his jaw broken in two places when he was on the wrong end of a punch in the locker room thrown by team-mate IK Enemkpali.
The Jets cut Enemkpali from their roster after the incident.
Smith is believed to have incurred the wrath of the linebacker after missing an appearance at his football camp in July.
Enemkpali purchased a plane ticket for Smith to attend the session in Texas, with an argument over the reimbursement of the flight fare sparking the attack.
"It was something very childish," head coach Todd Bowles said before Tuesday's practice.
"Something sixth graders could've talked about."
Smith, who posted a picture is expected to miss 6-10 weeks, with veteran Ryan Fitzpatrick set to deputise for the 24-year-old.
