How to throw a rear uppercut
The knockout punch from below — the rear hand drives up through the chin with the whole body behind it.
Action
Bend the knees and load the rear side, then explode upward: the rear leg extends, the hip turns over, and the rear fist travels in a tight vertical line under the guard to the chin, palm facing you, elbow tucked and pointing down. The lead hand stays high at the cheek. Land, then bring the fist straight back to the guard — do not let it hang in the air.
When to use
The classic finisher after the head comes down: behind a body shot, when the opponent is rocked and sagging forward, or as the last punch of a combination like 1-2-body-6. It is also a natural answer to an opponent who ducks under your straight punches.
Advantages
The most destructive single punch in the basic set — the force travels up through the legs, hip and back into the chin, the one target that turns the lights out. It also comes from below the guard, where most fighters keep almost no defence.
Limits
It needs distance control and a set-up: thrown from too far it becomes a slow swing that a hook beats easily. You drop your level to throw it, your head moves into hook range, and if it misses there is a long recovery with the rear side wide open.