That's because Diaz and Shields are both friends and training partners under Cesar Gracie -- not that the foul mouthed fight monger needs any extra motivation to challenge St. Pierre.
Diaz, who recently scored an improbable come-from-behind victory via first round technical knockout over British striker Paul "Semtex" Daley back on April 9, has been vocal about finding new challenges outside the Strikeforce promotion.
GSP tells the MMA Fight Corner (presented by Five Knuckles) to bring it on.
"I'm not scared of Nick Diaz. He wants a title shot that's why he says these things. He's not the first one that's been calling me out. I'm the champion now and everyone wants to have the title. It's a normal thing. I don't get into trash talk, but I'm not afraid of nobody. The UFC always gives me the best challengers and I welcome the challenge. Nick Diaz is very good. Great jiu-jitsu fighter, he's very good on the floor and he's got great boxing as well. He's the kind of guy, he's a very aggressive fighter. He likes to get in and open up on the head. He's a very good fighter and he's good at the mind game as well. He's one of the top guys."
There's been a lot of talk from the Zuffa brass about keeping the UFC and Strikeforce brands separate until the Showtime contract expires in 2014, but if Shields should fail, who else is in the UFC welterweight division that can give "Rush" a run for his money?
The Stockton, Calif., native is riding a 10-fight win streak and has finished all but one of his opponents in dominating fashion. Gracie even told HDNet that Diaz has a "re-worked" contract that allows him to dabble in the sport of boxing, where you don't have to worry about takedowns or lay 'n pray.
If Diaz gets crushed in the "sweet science," expect a hasty return to the cage. But will he be stuck in San Jose until the Showtime contract expires? Or can Zuffa finagle a "St. Pierre vs. Diaz" title unification bout?
And would Diaz have a chance if they did?
Your take on this fantasy fight?