Ronaldo was the hero once again as his powerful header was the decisive goal in the 3-2 win for the Red Devils.
It's not clear what the fans' motived were but he came very close to Ronaldo and briefly touched his jersey.
However, security were tackled the fan to the ground before any serious contact was made. Ronaldo appeared to see the funny side of the incident.
It capped off a crazy Champions League match which saw Ole Gunnar Solskjaer's men go in at half time 2-0 down.
But Man United, who defended poorly and were wasteful in front of goal in the first half, came out a different team.
Marcus Rashford slid the ball into the corner of the net after latching onto Bruno Fernandes' sublime through ball.
Harry Maguire then levelled the scores with a fine finish at Juan Musso's near post after Fernandes' cross unexpectantly dropped in the big centre-back's path.
And it was of course Ronaldo who had the final say as in true Ronaldo style he rose brilliantly to head in the winner.