Manchester United’s Marcus Rashford left a tactics note from Ole Gunnar Solskjær on the ground for Barcelona goalkeeper Marc-André ter Stegen to read.
The La Liga giants won 3-0 in Tuesday’s Champions League quarter-final second leg at the Camp Nou, triumphing 4-0 on aggregate.
As United chased the game, Solskjær decided on a change of formation and got first-team coach Kieran McKenna to write down the revised 4-4-2 line-up.
A note was passed on to Rashford, who carried it around with him until letting it slip from his grasp following a challenge with Gerard Piqué.
Spotting the instructions lying loose on the turf, ter Stegen picks it up and takes a look before scrunching it up and throwing it away.
It’s not clear whether he spread the word about the opposition switching the shape of their team.