It's an interesting clash of styles. Both men are highly competent boxers with equally dangerous jiu-jitsu skills. They're grapplers without being wrestlers, often eschewing that particular martial art in favor of more exciting fighting styles.
But who's better all around?
Some would say it's Penn, who famed boxing trainer Freddie Roach once called the very best boxer in all of MMA. Others would say Diaz, the foul-mouthed bad boy from Stockton who speaks softly and carries a big stick.
The person of the most interest, perhaps, believes that all things being equal, "The Prodigy" will get the job done -- as long as he comes at his best.
"I think BJ Penn will win the fight because I believe he has more skills. If he uses all his set of skills, then BJ Penn will win. But, the thing with BJ Penn is sometimes you don't know what BJ Penn will show up to the fight. If he's well prepared or injured - I don't know. Sometimes, I saw him perform very well at the best of his ability he's the best guy. But when he doesn't perform at the best of his ability he can be beat. Nick Diaz is very consistent, he has a similar style of fighting all the time. But, I believe if the right BJ Penn shows up, he'll win the fight."
Diaz, meanwhile, hasn't lost since 2007 and is currently riding a 10-fight win streak. That's about as impressive as it gets, even if the competition hasn't exactly been top of the line.
So who takes it, Maniacs? Penn or Diaz?