A four-minute smash and grab from Manchester United gave them a 2-1 win over Juventus, as former Bianconeri star Paul Pogba netted a 90th minute winner.
Over 41,000 packed into the Allianz Stadium as Cristiano Ronaldo bagged his third ever goal against his former club, but Juan Mata equalised late on, before an Alex Sandro own goal in the last minute gave United the win, as Juventus succumbed to their first group stage defeat at home since Bayern Munich in 2009/10.
The result opens up Group H with Juventus now just two points ahead of Manchester United, and Valencia a further two points off the English side.
There was an early onslaught from Juventus, as Leonardo Bonucci found Paulo Dybala on the edge of the area with a dinked ball, and the Argentine then lofted it to Cristiano Ronaldo, but his shot was blocked by Victor Lindelof.
Ronaldo was once again the main dangerman, and tried his luck from the edge of the penalty area, but his strike came off Chris Smalling’s face and went out for a corner. The Portuguese then had a go from distance which whistled just wide.
As the second half wore on Juve asserted their dominance over United and retained possession well. However, United were dangerous on the break.
Nemanja Matic chipped a lovely ball over the Juventus defence in the direction of Alexis Sanchez, but it had just too much on it and went out for a goal kick.
From there, Juventus went close to scoring. Sami Khedira got on the end of a Juve counter, but his strike was easily saved. Then David De Gea had to be alert as a Juan Cuadrado cross defected off Matic and needed a low stop from the Spaniard.
Just before the break, a Ronaldo cutback landed at the feet of Khedira, who was unmarked on the penalty spot, but he was unable to get his shot on target and it bounced off the post.
After the break, Juventus went close again as Dybala smashed the crossbar with an effort from distance.
Then just after the hour, Bonucci played a wonderful ball over the top for Ronaldo whose side-foot volley whistled past De Gea to open the scoring.
It was almost two moments later as Ronaldo dribbled into the area from he left, and found Miralem Pjanic on the 18-yard line, but his effort was well saved by De Gea.
Cuadrado should have made it two after he rushed forward with Ronaldo, but after a neat give and go with the No.7, he blasted over the bar from close range.
Pjanic saw an effort from distance whistle just over, but United levelled things up with four minutes left.
Pogo was fouled on the edge of the area and substitute Mata curled the resulting freekick over the wall and past Wojciech Szczesny and into the net.
Then in the final minute an Ashley Young freekick was headed on by Marouane Felliani into the path of Pogba who bundled home.
Marcus Rashford could have made it three, as he was sent in on goal but was denied by Szczesny.