Monza held visitors Inter Milan to a 1-1 draw on Sunday as the Italian champions were knocked off the Serie A summit.
Monza took the lead in the 81st minute through substitute forward Dany Mota, who headed the ball into the top corner before Denzel Dumfries levelled for Inter in the 88th from close range.
Inter dropped to second in the table with eight points after four games, one point behind Napoli who beat Cagliari 4-0 earlier on Sunday.