Michael Sam -- I Just Signed!!! With 'Dancing with the Stars'

Michael Sam will be competing in March, not on the football field, but on the "Dancing with the Stars" hardwood ... TMZ Sports has learned.

Michael -- the first openly gay player drafted in the NFL -- will be part of Season 20, which fires up next month.

Here's the problem. Sam -- who insinuated he was cut from the NFL because he is gay -- has vowed to get back in the league and said he'd take part in the first-ever veteran's combine on March 22.

But Sam needs to prove he has what it takes, and we're thinkin' some of the owners might question his commitment if he's focusing on the rumba rather than rumbling.