Jack Grealish was left out of Aston Villa's game against Newcastle, live on Sky Sports 1, due to a club suspension, Roberto di Matteo has confirmed.
Di Matteo said on Thursday that Grealish must "grow up" after confirming the club were conducting an internal investigation over reports of an alleged breach of club discipline by the midfielder.
Grealish, who signed a new four-year deal at Villa Park earlier this month, is alleged to have held a party in a Birmingham hotel hours after the club's goalless draw at Ipswich on Saturday, and Di Matteo has revealed the incident was behind the player's absence from his side's visit of Newcastle.
"He has been fined and suspended for today's game," Di Matteo told Sky Sports. "Tomorrow he will be back and available for selection."
West Midlands Police have confirmed officers attended the Park Regis Hotel at 7.45am on Sunday morning after other guests complained about "rowdy party", although no arrests were made.