That came from Greg Taylor's error, something Rangers forced as they harried and harrassed Celtic all over the park.
Nedim Bajrami gathered and fed Hamza Igamane. His shot was parried by Kasper Schmeichel and Bajrami touched in the loose ball not long before half-time.
At that stage, Rangers looked to have got this one absolutely right. Celtic had all the questions to answer.
What followed was bedlam. Two fighters, slugging it out until one could no longer continue.
Taylor was redeemed shortly after the break as his shot from the edge of the area deflected off Nicolas Raskin and past Butland.
That sparked something of a Celtic swarm. They smelled blood and, when Raskin casually nodded back toward Balogun, Maeda was ruthless to fire Celtic ahead.
The Ibrox side looked rocked. But, Celtic took a step back, Rangers took another forward and Mohamed Diomande turned and netted to level.
From there, it went back and forth with sheer will looking more decisive than any genuine quality.
It seemed Celtic's name would adorn this trophy, though, when Nicolas Kuhn linked with Arne Engels and found space to fire in what seemed destined to be the winner.
But inside a minute, Rangers found another incredible equaliser.
It was Danilo, so frustrated by injury for so long, who leapt to meet Vaclav Cerny's cross and gleefully haul his side back on terms.
Rangers' energy-sapping display against Spurs on Thursday came to mind during extra time, with Celtic having been afforded more rest after a Tuesday outing.
That told as Celtic finished the stronger, pinning Rangers back in their own half, but neither side could strike a decisive blow even though the Ibrox side claimed for a penalty when Liam Scales tugged back Vaclav Cerny.
But that moment came and went. As did the shootout.
Penalties require nerve, heroes and villains. Schmeichel was the hero. Yilmaz the unfortunate villain and Celtic were once more triumphant.