Gian Piero Gasparini's team in top form
|Argentinian striker Alejandro 'Papu' Gomez opened
the scoring in Atalanta's historic win
It was the biggest defeat Milan had suffered for 21 years. Atalanta’s goals came from Alejandro Gomez, Mario Pasalic, Josip Ilicic (two) and Luis Muriel.
Milan are struggling to mount a challenge at the moment, yet with 18 Serie A titles and seven European Cup/Champions League titles to their name remain one of the giants of Italian football.
They had not been beaten by such a margin in any competition since Roma beat them 5-0 in 1998.
Atalanta, by contrast, are enjoying one of the most successful periods in their 112-year history.
They are six-times winners of Serie B but only in recent seasons have begun to challenge the top teams in Serie A. Under head coach Gian Piero Gasparini, the nerazzurri finished fourth in Serie A in 2016-17 and took third place last season, qualifying to play in the Champions League for the first time.
The success has continued this season with Atalanta through to the knock-out stages in the Champions League after finishing runners-up to Manchester City in Group C.
In Serie A, they are up to fifth place with Sunday’s win, which again puts them in contention for one of the European competitions next season.
Atalanta play their home games at the Gewiss Stadium, the current name of the Atleti Azzurri d'Italia stadium in the Borgo Santa Caterina district of Bergamo, only a short walk from the centre of the city.