Originally published on ProWrestlingSheet.

Lucha Underground star Pentagon Jr. may not be able to wrestle using the new name he announced after leaving AAA ... because it's been trademarked by his former employer.

Lucha Libre FMV -- the company who owns AAA and Lucha Underground -- filed the documents one week after the wrestler announced he left their company and would now be known as Penta OM.

The document says the trademark is now live ... but, with the filing date being so recent, the wrestler still has time to file an opposition to fight their attempt to own his name.

According to Lucha Blog, the company also filed for the same trademark in Mexico.

We'll keep you updated if Penta OM fires back.