"Can ten years of imaginary training, pay off?" (starts good old fisticuffs with a gang of teens and kicks their asses) "It can."
Dae-su returns to the building where he had been imprisoned for fifteen years to find out who had done it and why. On his way out, after performing hack-job dental surgery on the guy-in-charge with a claw hammer, he beats the living daylights out of about twenty guys with said hammer and his fists and all with a knife stuck in his back for the second half of the fight. He then proceeds to pummel bloody the five more guys in an elevator - still with the knife in his back. The look on their faces when they see one man standing at the top of the corridor, admittedly bruised and cut up, but with all their friends writhing on the ground with broken limbs or concussions? Awesome...
For the director as well, given that the scene is nearly 5 minutes long, and is all filmed on one camera, in one take. The fight sequence took three days worth of attempts to nail.
"You see, they say that people shrivel up because they have an imagination. So, don't imagine anything, you'll become brave as hell."
The scene in which the main character anticipates his enemy's trap and kills two of his bodyguards with a toothbrush.
Dae-su vs Mr. Han. For all his conditioning and rage, it can't stand up to the skills of Woo-jin's top enforcer. But even when thrown across the room and into a window. Dae-su refuses to give in and fights on, managing to stab Han in the ear with a pair of scissors and making the stoic albino undergo a magnificent Villainous Breakdown. Which Woo-jin calmly interrupts as he's about to kill Dae-su by shooting him in the head.
"If by any chance Mido should find out the truth, you son of a bitch, I'm going to rip you limb from limb. And your remains will never be found. Why? Because I'm going to swallow every last bit!"