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

The Hawks listed Young on their injury report that night as out due to tendonitis 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 for which Young would qualify because he was the last to be an All-Star selection was. season. According to league rule, “unless a team demonstrates an approved reason for a star player not to participate in a game,” a 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 determined that the Hawks held Young out of a game in which he could have played based on the medical standard in the policy,” the league said. “The organization’s conduct violated its policies, which are intended to promote participation in the NBA regular season.”

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