In an entertaining game both sides had their chances before the Championship outfit hit Boro with three goals in nine devastating second-half minutes.
Graham Westley recalled Luke Jones, Darius Charles and Jordan Burrow to an attacking starting XI that saw Dani Lopez dropping off just behind the front two and Sam Wedgbury and Luke Freeman providing the width.
There was a great atmosphere around the ground at kick-off and the packed away support thought their team had gone ahead within 60 seconds when the ball was bundled home. Fortunately the ref's whistle had long gone for an infringement and the score remained 0-0.
The teams traded half chances in the opening exchanges before Boro's front three combined brilliantly on 20 minutes. A Burrow header was played through by Lopez to Tounkara who looked to be taken down, but both the referee and linesman waved played on.
Minutes late Jon Ashton met a Luke Freeman corner with a firm header which looked like finding the back of the net until a defender's body got in the way.
An acrobatic effort from Luke Varney was saved comfortably by Chris Day as the visitors responded, but this wasn't to be the last we'd see of the experienced front man in this game.
Both teams continued to create chances with Tansey firing just wide past a wrong-footed Paddy Kenny after a surging run down the right by Sam Wedgbury, whilst heroic Boro defending kept out Leeds at the other end after a scramble in the box.
Despite all the goalmouth action the game somehow reached half time goalless.
Boro began the second half brightly with Tounkara seeing a shot deflect behind and then from the resulting corner Dani Lopez saw a header saved.
Leeds continued to press forward but were thwarted again by good Boro defending. Jon Ashton holding off Aiden White on one occasion when it looked like the pacey winger would simply brush past Boro's skipper.
Paddy Kenny saved from a dangerous Freeman free-kick from the edge of the box before the visitors struck on 70 minutes. A cross from Rodolph Austin on the right found Varney whose powerful header found the back of the net.
Tounkara fired over as the hosts looked for an equaliser before Boro were undone minutes later by a bit of quick-thinking by Leeds. A swiftly taken free-kick, following an offside decision against Boro, found Varney onside and the striker took a touch before firing in off the post.
Minutes later and Leeds found themselves with a spot kick. Two Boro defenders were harshly penalised for challenging strongly for a header in the box and Varney stepped up to complete a clinical treble.
Frenchman Tounkara had a chance to pull one back for Boro but fired just wide of Paddy Kenny's right-hand post after bursting through the Leeds defence.
Ultimately three goals in a deadly nine minute spell was the different in this game with Boro otherwise matching their Championship opposition.
Next up for Graham Westley's men is a Manchester United XI on Friday night featuring some of the Premier League champions best young talent. Kick-off at The Lamex is 7.45pm.
Boro: Day, Wedgbury (Deaman), Jones (Deacon), Ashton, Charles, Freeman (Bruna), Tansey (Dunne), Heslop, Lopez (Shroot), Tounkara, Burrow (Hills)
Subs not used: Thompson (GK), Akins
Leeds: Kenny, Drury, Lees, Green (Austin), Varney (Hunt), White, Pugh, Brown, Norris (McCormack (Murphy)), Thompson, Poleon