The Italian Champions’ seven-match winning streak in the league came to an end as they were held by Atalanta in their second Serie A game of the season.
Ruslan Malinovskyi scored the game’s first goal with a strong left-foot finish from 20 yards out.
Napoli and Inter Milan lead the rest of the pack with six points from two games with Milan sitting close two points behind them.
AC Milan will play Bologna in their next Seria A game, while Atalanta lock horns with Verona.
AC Milan will be looking to win back-to-back titles for the first time since 1992-93 and 1993-94 following their triumph last season.