Milan ensured they will end 2020 atop Serie A as Theo Hernandez's stoppage-time goal secured a 3-2 win over Lazio at San Siro on Wednesday.
Stefano Pioli's side wasted little time stamping their authority on the game, racing into a two-goal lead inside 17 minutes courtesy of Ante Rebic's header and Hakan Calhanoglu's penalty.
Luis Alberto and Ciro Immobile – who had a spot-kick saved prior to the Spaniard's goal – restored parity by finding the net either side of the interval, but Hernandez powered home from a corner in the 92nd minute to dramatically seal the three points for the Rossoneri.
The result restored Milan's one-point lead at the Serie A summit after neighbours Inter had temporarily leapfrogged them following a 2-1 win over Hellas Verona earlier in the day.
Milan were rewarded for their bright start after 10 minutes when Rebic lost his marker from Calhanoglu's corner and headed home his first goal of the season from six yards.
Calhanoglu added a second seven minutes later, the Turkey international slotting into Pepe Reina's bottom-left corner from 12 yards after Rebic had been fouled in the area by Patric.
Lazio reduced the deficit in the 27th minute when Luis Alberto headed in after Immobile's penalty had been pushed onto the post by Gianluigi Donnarumma, the spot-kick given for a foul by Pierre Kalulu on Joaquin Correa.
Milan's lead was then wiped out in the 59th minute when Immobile's volley from Sergej Milinkovic-Savic's lofted ball into the area squirmed past Donnarumma.
Rebic missed two glorious opportunities in the final five minutes, but it mattered little in the end as Hernandez rose highest to head home Calhanoglu's corner and spark delirium on the Milan bench.
What does it mean? Relentless Milan march on
They were pushed all the way by a tough Lazio outfit, but Milan prevailed to register a 10th win in 14 Serie A games this season and reclaim their place at the summit from Inter.
Another two-goal haul, meanwhile, made them only the second team in the history of the top five European leagues to score more than once in 16 consecutive games in a single calendar year, with Barcelona managing 18 in 1948.
Calhanoglu sparkles for hosts
Calhanoglu was at the heart of everything positive for Milan. The 26-year-old scored his first league goal of the season from the spot and assisted the Rossoneri's other two. In total he created four chances for team-mates and completed the most passes of any home player (45).
Calabria endures a game to forget
Davide Calabria struggled for the hosts, losing possession a game-high 20 times and completing just 63.9 per cent of his passes – the second fewest of any Milan player.
Both sides return to action following the mid-season break on January 3, with Milan travelling to Benevento and Lazio visiting Genoa.