The NBA fined the Atlanta Hawks $100,000 on Tuesday after an investigation revealed that guard Trae Young may have played in an NBA Cup game against the Boston Celtics on Nov. 12.

The Hawks listed Young on their injury report that evening as out due to tendinitis in his right Achilles tendon. Atlanta still won the game 117-116.

The problem, the NBA said, was that the Hawks violated the league’s player participation policy — which focuses primarily on what the league defines as star players, a group Young would qualify for since he was last in The All-Star selection was the season. According to the league’s rules, “unless a team demonstrates an accepted reason for a star player not participating in a game,” the team must have the star players “for all nationally televised and NBA in-season tournament games.”

“After an investigation, including review by an independent physician, the NBA concluded that the Hawks excluded Young from a game in which he could have participated in accordance with the policy’s medical standards,” the league said. “The organization’s conduct violated the policy designed to encourage participation in the NBA regular season.”

This game against the Celtics is the only one Young has missed this season.