A Boxer has no counter in his repertoire against your chin-na

If you apply chin-na on Karate opponents, they have no techniques in their repertoire to respond to your attack. This does not necessarily mean that if you know chin-na, you will surely defeat them. If they are moiré skillful, such as being faster and more forceful than you, they will still beat you. "Old Eagle Catches Snake" is an effective chin-na technique against Karate punches.