Match ends, Atalanta 2, Milan 1.
AC Milan players had bananas thrown at them during a 2-1 defeat at Atalanta.
Guinea international Kevin Constant and Netherlands midfielder Nigel de Jong picked up two bananas thrown onto the pitch, while Milan players appeared to sarcastically applaud the home support.
Fans were warned the game would be suspended if there was a repeat.
"Whoever threw the banana on the pitch deserves to have a coconut thrown back at them," Atalanta boss Stefano Colantuono told Gazzetta dello Sport.
"They've ruined what was a great afternoon."
Milan boss Clarence Seedorf said: "I hope they find the culprit and do what they have to do."
Constant was on the receiving end of racist abuse during a pre-season tournament match against fellow Serie A side Sassuolo in July.
On that occasion, the 27-year-old kicked the ball into the crowd and left the pitch. He was fined 3,000 euros (£2,500), with Sassuolo fined 10 times that amount.
Two weeks ago, Barcelona defender Dani Alves picked up and ate a banana thrown at him by a Villarreal fan.
Footballers worldwide showed their support for the Brazilian by posting pictures online of themselves eating bananas, while Villarreal were fined 12,000 euros (£9,850) by the Spanish Football Federation.
Milan's defeat in Bergamo hit their hopes of qualifying for next season's Europa League.
A Gianpaolo Bellini own goal after 51 minutes put the visitors ahead.
German Denis equalised with a 68th-minute penalty after Constant fouled Carlos Carmona, shortly before the bananas were thrown onto the pitch.
Milan's Mario Balotelli hit the post late on before Franco Brienza's 25-yard strike flew into the top corner to clinch victory for Atalanta in the sixth minute of stoppage time.
- 77RaimondiBooked at 69mins
- 18BaselliSubstituted forMigliaccioat 74'minutesBooked at 85mins
- 11MoralezSubstituted forBrienzaat 88'minutes
- 10BonaventuraSubstituted forDe Lucaat 68'minutes
- 27Del Grosso
- 91De Luca
- 2De Sciglio
- 34de Jong
- 5MexesBooked at 69mins
- 10HondaSubstituted forEl Shaarawyat 45'minutes
- 22Dos Santos LeiteSubstituted forPazziniat 80'minutes
- 4MuntariSubstituted forTaarabtat 76'minutesBooked at 90mins
- 7de Souza
- 59Vasconcellos Ferreira
- 92El Shaarawy
- Nicola Rizzoli
- Shots on Target
Second Half ends, Atalanta 2, Milan 1.
Goal! Atalanta 2, Milan 1. Franco Brienza (Atalanta) left footed shot from outside the box to the top left corner. Assisted by Giulio Migliaccio.
Foul by Philippe Mexes (Milan).
Giuseppe De Luca (Atalanta) wins a free kick in the defensive half.
Corner, Milan. Conceded by Yohan Benalouane.
Attempt blocked. Mario Balotelli (Milan) right footed shot from outside the box is blocked. Assisted by Kevin Constant.
Offside, Atalanta. Luca Cigarini tries a through ball, but Germán Denis is caught offside.
Adel Taarabt (Milan) is shown the yellow card for a bad foul.
Foul by Adel Taarabt (Milan).
Franco Brienza (Atalanta) wins a free kick on the left wing.
Foul by Mario Balotelli (Milan).
Gianpaolo Bellini (Atalanta) wins a free kick in the defensive half.
Attempt missed. Mario Balotelli (Milan) right footed shot from the right side of the box misses to the right.
Mario Balotelli (Milan) hits the left post with a right footed shot from long range on the right. Assisted by Mattia De Sciglio.
Offside, Milan. Adel Taarabt tries a through ball, but Giampaolo Pazzini is caught offside.
Foul by Adel Taarabt (Milan).
Luca Cigarini (Atalanta) wins a free kick in the defensive half.
Substitution, Atalanta. Franco Brienza replaces Maximiliano Moralez.
Attempt missed. Mario Balotelli (Milan) right footed shot from outside the box is just a bit too high. Assisted by Adel Taarabt.