The Serie A side entertain Paris Saint-Germain at the San Siro on Tuesday night in the Champions League.
According to Italian outlet Sport Mediaset, AC Milan ultras will wear No.71 shirts.
The move alludes to the Neapolitan method of deriving lottery winning numbers from dreams.
It is called Smorfia Napoletana in Italian, with 71 meaning 'man without values'.
Additionally, they will toss fictitious cash in the direction of the shot-stopper to draw attention to what they believe is his treachery.
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Donnarumma came through the ranks at the Serie A club before making a controversial free transfer to PSG in 2021.
The 24-year-old played 251 games for the club and won the Italian Super Cup in the 2016/17 season before leaving for the French capital.
His boyhood club did offer him a deal in the region of £120,000 per week, but he turned it down in favour of a switch to the Parc des Princes.
He will now be tasked with stopping his former club in Europe's elite competition as PSG look to make it to the knockout stage.
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PSG chairman Nasser Al-Khelaifi recently heaped praise on the goalkeeper and believes he should be shown respect on his return.
"Gigi is one of the best goalkeepers in the world. He's still so young and such a great professional, he's also a fantastic person," he told Gazetta dello Sport.
"What he contributed to AC Milan over 215 appearances was amazing - and I have huge respect for both AC Milan and Gigio."
The Ligue 1 champions are at the top of Group F with six points, with AC Milan sitting bottom behind both Borussia Dortmund and Newcastle.
The reverse fixture saw the French champions claim a comfortable 3-0 win over the seven-time European champions.