'Masked Singer' Alum, Hunter Hayes, Shares Pep Talk with Bull

As the "Masked Singer" finale heats up, former contestant Hunter Hayes -- who was Astronaut on the show -- has a special message for Bull ... and TMZ's delivering it.

Next week, we will see who takes the winning spot, and our 'Masked' sources tell us Bull's chosen to perform Hunter's tune, "Invisible" because he feels a strong connection to it.

That prompted the singer/songwriter to record this heartfelt pep talk before Bull steps into the ring for his final performance.

In the video, Hayes congratulates Bull on getting this close to the title, saying ... "I'm excited for you and for the world to hear your voice." He also made sure to thank him for fighting for his song selection.

Apparently, Bull wants to win so bad, that he is overwhelmed with nerves... we'll see if Hunter's words of inspiration are enough to help him take home the W.