Rafael Leao scored the fastest goal in Serie A history to put Milan ahead at Sassuolo on Sunday, netting after just six seconds.
The forward put an emphatic finishing touch to a Milan charge through the Sassuolo ranks, with Brahim Diaz playing the kick-off short to Hakan Calhanoglu, who raced straight towards the penalty area.
Calhanoglu's pass through to Leao was smashed in, leaving the home side shell-shocked.
Milan began the game at the top of Serie A.
Sassuolo had not touched the ball by the time Leao found the back of the net, in what looked to be a pre-planned move from the kick-off.
Opta confirmed it was the fastest goal ever in Serie A, stating it broke the previous record of eight seconds, which was set by Paolo Poggi for Piacenza against Fiorentina in 2001.
Calhanoglu had a goal disallowed for Milan in the ninth minute as Stefano Pioli's team looked to build on their fast start.
They pulled 2-0 clear in the 26th minute, however, with Alexis Saelemaekers on target.