Go to the "My Corner" screen, then go to options. Turn on the 3 knock out rule. Knock your opponent down three times in the first round. Try to do this as fast as possible and beat 59 seconds. You should now have the fastest KO record.

Start a new career and go pro immediately. Go to the settings and turn on 3 knockdown (T.K.O.). Fight the rank 49 boxer and constantly Haymaker him. If he starts blocking, do a Haymaker on the other side. Once you are in Knockdown mode you will need one more Haymaker to knock him down. Once he gets back up it will take about four Haymakers to knock him down again. Try to knock him out in 59 seconds to get the fastest knock out record.