Ray Rice -- Training His Ass Off ... At Elite Fitness Center (Video)

Ray Rice is clearly expecting to return to the NFL -- training every single day at an exclusive athletic facility in Connecticut ... TMZ Sports has learned.

The former Baltimore Ravens running back is a regular at the BlueStreak Sports Training Center in Stamford, CT ... and we're told he's been impressive with speed and footwork drills.

We're told Rice has been at the center for the past "few months."

Rice is eligible to play in the NFL again after serving his suspension for the domestic violence incident -- but the question now ... is there a team that will actually take a chance on Rice?

Stay tuned ...