Holly Holm: I'M RIPPED ... And Ready for Rousey

NO TURNING BACK NOW!!!

UFC star Holly Holm is about to board a plane to Australia ... where she's set to take on Ronda Rousey next weekend ... and we gotta say, she looks like she's been training her ass off!

Holm just took this photo after her last hardcore training session and wrote -- "Time to head to Melbourne this evening. What a journey already and the fight is still to come. I love my life and this journey I am on."

Rousey and Holm are set to battle in Melbourne on Nov. 14th.