Joao Morelli fired Boro into the lead on 15 minutes at a wet Rockliffe Park, but we responded shortly before the hour mark when Milos Veljkovic played in Shaq Coulthirst to strike home.
Anton Walkes netted the winning goal 10 minutes from time, converting Andros Townsend's cross.
Middlesbrough U21s: Fryer, Johnson, Fry, Elsdon, McGinley (Coulson 68), Tinkler (c), Chapman, Morris, Morelli (Jakupovic 72), Maloney (Wheatley 81), Mondal. Substitutes (not used): Coddington, Jowers.
Spurs U21s: Voss, Walker-Peters, Georgiou, Lesniak, Veljkovic (c), Amos, Townsend, Walkes, Coulthirst (Goddard 88), Harrison (J Pritchard 83), Sonupe (Miller 77). Substitute (not used): McDermott (GK).
Above: Kyle Walker-Peters battles with Junior Mondal.
NEXT MONDAY: Watch our Under-21s' clash with Southampton at Stevenage FC, live and in full on Spurs TV!
On air from 6.30pm, we kick-off at 7pm. Don't miss it!