1. Forthright and honest
   "had a man-to-man talk about the facts of life"
    
2. (sport) being a system of play in which an individual defensive player guards an individual offensive player
   "man-to-man defence";
   - one-on-one

1. Straightforwardly or frankly
   "we must talk man-to-man"

See also: case-by-case, direct, individual, item-by-item, single

Encyclopedia: Man-to-man