Milan beat Barcelona 4-3 on penalties after a 2-2 friendly draw in which Robert Lewandowski scored twice for the Blaugrana.
The Rossoneri stormed into a 2-0 lead inside 15 minutes at M&T Bank Stadium on Tuesday.
Having teed up Luka Jovic's opener with a neat ball across the six-yard box, United States star Christian Pulisic further delighted the American crowd with a dazzling run and finish to double Milan's lead.
Cutting in from the left, Pulisic skipped beyond his marker before lashing a fine effort high into the roof of the net from a tight angle.
Yet Barca were back in the contest in the 22nd minute when Lewandowski coolly picked out the bottom-right corner from the edge of the area.
A slick move from Hansi Flick's team saw them draw level midway through the second half - Pau Victor laying it up for Lewandowski to tap home.
But with Lewandowski off the pitch, Barca could not get over the line in the shootout, with Mikayil Faye seeing the decisive penalty saved.
Data Debrief: Blaugrana can take the positives
Despite the shootout loss and the sluggish start, it was an excellent performance for much of the match from Barca, who had 17 shots to Milan's four and created 1.72 expected goals.
That being said, Milan's xG (1.02) shows that the Rossoneri did get into good positions despite their low shot count, and Barca will have to tighten up defensively ahead of their LaLiga campaign.
