The Brazilian model was heading to her shoot in Las Vegas in her sexy Christmas attire -- a decorative thong bikini with a "Naughty" Santa hat to boot -- and strapped on some roller skates to make a more memorable entrance.

Not a great idea, but then again ... it worked!!!

Liziane lost her balance -- and the prop Xmas gifts -- and had herself a scary little tumble. Good news is, it looks like she escaped serious injuries in the slip and fall ... which is a welcome change of fortune for her.

The model had another rough year, medically speaking, with a botched plastic surgery in March that led to facial swelling and required an additional procedure to reverse the damage.

This came less than a year after she survived slipping into a coma after a liposuction procedure went awry.