Chicago ? A man who pleaded innocent in the father-son beating of a Kansas City Royals coach changed his plea to guilty Tuesday and will be sentenced June 18.

William Ligue Jr. was charged with two counts of aggravated battery last September after leading his teenage son onto the field at a Chicago White Sox game and beating Tom Gamboa, who was coaching at first base.

Ligue’s son, released to his mother’s custody, was sentenced to five years’ probation and 30 hours of community service. Before his sentencing, Gamboa advocated probation rather than prison.

The change of plea was unexpected and not part of a plea agreement.