Britney Spears Smolders in Tiny Red Thong and See-Through Lingerie

Britney Spears did not leave much to the imagination in her latest Instagram post -- sporting a teeny tiny red thong ... and maybe even commenting on all her biopic casting rumors.

Brit changed it up Friday night when, instead of her usual dancing video, she posted a series of sexy shots in the thong and black lacy lingerie, with the caption ... "Definitely a character because that’s not me !!! But wait shit it does kinda look like me 🤔🤔🙄🙄 !!! Just kidding !!!"

It's not entirely clear what she meant ... but perhaps she was commenting on the casting rumors of her upcoming biopic directed by "Wicked's" Jon M. Chu.

If the gossip is to be believed ... Sabrina Carpenter and Millie Bobby Brown are among the actresses being considered for the role -- that Brit herself has the final say over. Of course, no one really knows where the process is at this point.

As for the new sexy snaps ... it's clear Britney has a new favorite spot in her house to make social posts ... 'cause she keeps heating things up in front of that huge fireplace!