Forward Ante Rebic broke his AC Milan duck by scoring two second-half goals including a stoppage-time winner to give them a thrilling 3-2 win over Udinese in Serie A on Sunday.
Milan, with Zlatan Ibrahimovic starting for the first time since returning to the club for a six-month loan, made a terrible start as they went behind after six minutes.
Rebic came on at halftime and levelled from close range within three minutes, his first goal since joining on loan from Eintracht Frankfurt at the start of the season.
Donnarumma made amends for his mistake with saves from Rolando Mandragora and Stefano Okaka before Theo Hernandez rifled Milan in front from outside the area, meeting the ball first time after a clearance was headed straight to him.
Ibrahimovic fired over from Rafael Leao‘s pass before Lasagna silenced the San Siro by heading Udinese level in the 85th minute.
But Rebic had the final word when he collected a loose ball on the edge of the area and threaded his shot through a pack of defenders and into the bottom corner.