'Bachelor' Star Juan Pablo Galavis -- Bring On the Hot Model Ass

This hot piece of model ass belongs to Nikki Ferrell ... one of the chicks gunning to bang new "Bachelor" Juan Pablo Galavis ... and from the looks of things, she's a frontrunner.

Nikki (according to various reports) is a 26-year-old model from Kansas City ... who was spotted with the former pro soccer player in Miami this weekend.

Galavis appeared on "The Bachelorette" last season, but didn't crack the final 5.

Sometimes, ya gotta lose to win.