AC Milan lost 1-0 at Udinese in the Italian league on Saturday and failed to boost its confidence ahead of Tuesday's Champions League clash at Atletico Madrid.
Antonio Di Natale scored the only goal of the game in the 66th minute, finishing off a great team move by Udinese.
Milan enjoyed the best opportunities in the first half and forced teenage goalkeeper Simone Scuffet into several fine saves, most notably denying Giampaolo Pazzini from close range with a one-handed stop.
Cristian Zapata should have given Milan the lead moments earlier but headed a corner wide after being left unmarked at the far post.
Scuffet also made a superb diving save shortly after halftime to parry Robinho's header from point-blank range.
Milan goalkeeper Christian Abbiati — who made his league debut when Scuffet was only two years old — pulled off a brilliant save to deny Roberto Pereyra early on.
Udinese improved after the break and took the lead when Pereyra released Bruno Fernandes, who crossed for an unmarked Di Natale to slot home.
Substitute Mario Balotelli blasted over the bar shortly afterwards for Milan, while Allan curled an effort narrowly past the top corner for Udinese.
Milan remained provisionally 10th after its second successive league defeat. Udinese moved 13th with its first win in four matches.
Relegation-threatened Catania hosts Cagliari later.