If you can understand Portuguese then you should check out this Brazilian UFC video of Anderson Silva talking about the toughest fight of his career. If you understand comic book lingo, then you should definitely check out this Brazilian UFC video for the sole purpose of identifying what shirt Anderson Silva is rocking in studio. If none of the following apply to you, then check out this translated excerpt from the interview where Anderson Silva states the toughest fight of his career was not against Chael Sonnen, but Mach Sakurai.
"No, my toughest fight in my career was against Hayato Sakurai in Shooto, my second toughest fight in my career was against Rich Franklin, it was a difficult fight for me. He’s a smart fighter, he knows the correct moments to throw the strikes and where they are effective."
And just like that, I found the Anderson Silva vs. Mach Sakurai match on YouTube. This internet and its ability to instantly gratify everyone on the face on the planet, got to love it. Mach Sakurai also has a homemade sex-tape floating around on the internet that I'm sure you can find if you do a little Googling (or raid my computer's hard drive). [Source]