Originally Posted by Ghost

well if the rear is the right uppercut then with the left hook with a half backstep off the rear leg and a slight layback.
You stay in range of their uppercut but in order for them to hit you they have to react to the change in range and convert to a long uppercut and even if it does hit you are moving with it. But with any luck you will beat them to it as you are using your front hand.
If its their left hand that is rear be it a southpaw or they happen to be in that position then its hard as you cant reach their head with your back hand while staying out of range. As you are both trying to hit with your back hand.
So id hit with the long left uppercut using the same general footwork and body movement as above.
THere is also the elbow stepping in as the elbow covert to protect the lower jaw.
Peter aerts does a medium/short range head kick but not everyone can pull it off ( i struggle to but im not flexible enough really). He does it off the left with little or no footswitch, but its an option too.

Cant think of others off the top of my head. Can you?
dont do a list of 1000 lol ill be embarrased.