Straight from the champ's mouth ... Amanda Nunes says she wants to get in the Octagon with Ronda Rousey as soon as possible -- if Ronda actually fights again.
Nunes -- who just beat Miesha Tate to win the Women's bantamweight title -- was doing a media event for UFC 201 and was asked who she would pick for her first title defense.
Nunes didn't hesitate -- "Ronda Rousey" ... but only IF the UFC legend decides to fight again.
Nunes says it's important for her to square off with Ronda "to prove to everybody one more time I deserve to be here."
If Ronda doesn't fight again, Nunes says she already has a Plan B -- Julianna Pena -- but says she'd beat JP's ass ... "no problem."