The controls are still the same, revolving around moving the analog stick like a pair of punching arms - flicking it to the right and circling upward, for example, busts out a right hook. The careful ebb and flow of blocking and punching is still there as well, but the action feels a lot more unforgiving, and you'll have to think fast to parry and counter nonstop fist barrages.
The only real indication of how you're doing during these matches will be your vision, which gets progressively cloudier and wilder as you absorb more and more punches. Each powerful hook or haymaker not only snaps your view briefly away from your opponent, but also comes with an assortment of blinding red flashes that will be familiar to anyone who's ever had a concussion. If your eyesight dwindles down to a red-tinted tunnel surrounded by crimson clouds, it might be a good idea to throw in the towel - unless of course your opponent is covered in more blood and swollen lumps than you, in which case fight on.