Another change followed as the next board flashed: 17 off, 10 on.
Luka Modrić stepping in for Lucas Vázquez.
A ripple of anticipation went through the Bernabéu faithful, applause swelling for the old master.
But then came a stir, an uproar even. 11 off, 21 on. Rodrygo's number lit up, replaced by Brahim Díaz.
Instantly, the mood shifted.
Boos rained from the south stand, whistles piercing the air.
Rodrygo, visibly frustrated, jogged off without his usual clap to the crowd.
His teammates gave him pats on the back, but the fans weren't hiding their discontent.
He had been Madrid's sharpest blade since the second goal, his dribbles carving at Arsenal's back line, and to see him withdrawn so soon felt sacrilegious.
"You can hear the discontent loud and clear," Ian Darke said over the din. "Rodrygo has been their livewire… this will not sit well with the supporters."
