This is for the fastest knockout in a One-Player game versus the computer.

Difficulty switch must be set to the B position. This means players fight an opponent who is "weaker and easier to beat" than the A position.

Players can select any of the available boxers, both for themselves and for their opponent

The in-game clock is used for this challenge rather than real-world time. 

The timer begins at 3:00 minutes per round.
When boxers are knocked down, the ref count will appear in place of the clock. If the count goes to 10, the floored boxer is KO'd and the remaining final time for that round will appear. 

The submission score is calculated by subtracting the remaining time (as displayed) from the maximum time available from the rounds fought.

For example: If players KO their opponent in the third round and the clock shows 1:10 remaining, the overall completion time will be 7:50 minutes. (Each round is 3 minutes, so 3 x 3-minute rounds equals 9-minutes minus the 1:10-minutes that was remaining in the third round at the time of the knockout).