There was probably only two sports where both the US and Japan are traditionally strong, those being baseball and softball. Table tennis, smimming, gymnastics or whatever can't compare. Japan is of course good in judo and karate but not the US. It is baseball and by extension softball, where there is a large following and regularly televised seasons every year in both Japan and the US. In the Olympic finals of both matches following elimination rounds, it became US vs Japan. This is the highest degree of rivalry but a good and friendly yet intense rivelry. Japan won Gold in both. Although, had the US falling short of a gold in the total tally vs China, it might have been better had Japan taken silver in one of them instead. Fortunately, the US didn't need it in the end.