A brilliant strike by teenager Manuel Locatelli fired AC Milan to a hard-earned 1-0 win over Serie A leaders Juventus at the San Siro.
Milan had lost their last nine matches against the Bianconeri, including last season's Coppa Italia final.
However, 18-year-old midfielder Locatelli blasted the ball past veteran goalkeeper Gianluigi Buffon on 65 minutes to secure a first win over Juve since November 2012 as Vincenzo Montella's young side continued their impressive start to the season.
However, the outcome could have been different after a first-half free-kick from Juventus midfielder Miralem Pjanic was controversially disallowed for what looked a tight offside call, having initially been given by the officials.
Milan move up into second place, two points behind Juve and three ahead of Roma, who host Palermo on Sunday night.
In Saturday's earlier kick-off, Sampdoria claimed their first win for seven Serie A games with a 2-1 victory over local-rivals Genoa in the Derby della Lanterna at the Stadio Luigi Ferraris.
Colombian striker Luis Muriel gave the hosts an early lead from close range after 12 minutes before Genoa midfielder Luca Rigoni equalised on 24 minutes when he turned in Edenilson's cross.
Sampdoria were awarded a penalty on the stroke of half-time after goalkeeper Mattia Perin fouled Fabio Quagliarella. The 23-year-old stopper, though, made up for his error and saved the resulting spot-kick.
However, the hosts were not to be denied as an own goal from Genoa defender Armando Izzo two minutes into the second half proved enough to secure victory and ease the pressure on Sampdoria manager Marco Giampaolo.