You have to be more careful, Marcus.
In the second-half, with Manchester United trailing to Barcelona, Ole Gunnar Solskjaer handed Marcus Rashford a note with instructions on from the touchline.
The striker dropped it after reading the piece of paper. A bored Marc-André ter Stegen then picked it up and read it in hilarious scenes.
What was written on the note?
Well, the note shows that the United boss wanted his side to switch formations. It had the names of his players in a 4-4-2 formation.
So, nothing too revealing but you have to be more careful in the future, Marcus.
Ultimately, Solskjaer tweaking his tactics failed to influence the match as Barcelona beat United 3-0 on the night and 4-0 on aggregate.
Lionel Messi scored a first-half brace including a superb strike to open the scoring with ex-Liverpool man Philippe Coutinho also getting on the score-sheet.
The Brazilian curled in a beauty from 25-yards out in trademark fashion.
Barcelona will now face Liverpool for a spot in the Champions League final.
The La Liga club entertain Liverpool on May 1 before visiting Anfield on May 7.
Who's heading to Madrid? Let us know what you think in the comment section below.