Udinese checked AC Milan's rise up the Serie A table by holding the Rossoneri to a 1-1 draw at San Siro.
Former Rossoneri defender Pablo Armero made life difficult for Sinisa Mihajlovic's men, who had been pursuing a third straight win, with his first-half opener and Milan struggled to respond.
M'Baye Niang did fire an equaliser shortly after half-time but the hosts had missed an opportunity to close the gap on the nearest Champions League place to just four points.
Armero's goal arrived in the 18th minute, the Colombian hurting the club he played for on loan last season with a tap-in after Zdravko Kuzmanovic had seen his attempt pushed onto the bar by Gianluigi Donnarumma.
Udinese retreated and allowed Milan no quarter before the break, after which Niang managed to find a gap.
The French forward spearheaded a counter-attack and was in the best position of all his team-mates to turn Carlos Bacca's through-ball beyond Orestis Karnezis. It was a third goal in as many games for Niang.
Karnezis was soon needed to pull off a superb save to keep Mario Balotelli's free-kick, and then Bacca's follow-up, out of his net shortly before the hour mark.
As time ticked away Milan attempted to turn the screw but Karnezis narrowed his focus to repel both Riccardo Montolivo and Kevin-Prince Boateng in the space of a few minutes.
Club captain Montolivo came knocking again in stoppage time, but Karnezis saved Udinese once again by pushing the midfielder's first-time drive to safety.