Peyton Manning's still showing off his skills ... in the karaoke department, 'cause he jumped on a stage to bust out his old University of Tennessee fave "Rocky Top."
Manning hit up Winners -- a popular Nashville honky tonk -- on Monday night and joined country star Lee Brice and his band to sing lead on the Volunteers' traditional song.
Retirement looks good on Peyton. As for how it sounds? Ehhhh ... give it a listen.