I just finished this one 2 days ago.
After the low blow (or a few) against very skilled boxers (Ali, Frazier) take a step back and get them off of you. A few elbows to the head followed by low blows (Add a hay maker or two as well) will have the fight stopped if not in the first round for sure early in the second.
You have to time your attacks and it'll be so easy.
Very easy 1000