The Rossoneri made the mistake of including Stephan El Shaarawy as one of their 'A list' players when they could have classed the Italy international as a 'B list' player
AC Milan director Umberto Gandini has taken responsibility for the blunder that has robbed M'Baye Niang of the chance to represent the club in this season's Champions League group stages.
The Rossoneri finalised their 25-strong squad on Tuesday but made the mistake of including Stephan El Shaarawy as an 'A List' player when the Italy international could have just have easily been named in the 'B List', thus creating an extra berth for Niang.
"Umberto Gandini regrets this error and apologises to all parties concerned, as well as professionally to the Rossoneri fans."
Niang is therefore ineligible for Milan's upcoming Group H clashes with Barcelona, Ajax and Celtic.