Outsiders Belvedere put it up to the more-fancied Terenure from the off and fittingly crossed for the try of the game in the process.
In the opening minutes, though, deft play by Terenure led to a concerted drive by their pack which saw hooker Andy Roche go over the line for the first try of the game.
It did not open the floodgates but 'Nure's pack remained impressive and 53 minutes in they got their reward by way of a second well-engineered push-over try, a near copy of the first, with Roche going over again after good work from a line-out.
Billy Dardis added a successful penalty in the 61st minute and at 13-0 the pre-tournament favourites seemed home and hosed.
But just four minutes later the most delicately timed and delivered Ross McDermott pass to Ger Young, at full tilt on a clever inside angle, cut the much-vaunted Terenure midfield apart.
It made for a brilliant try and no more than Young and Belvo deserved as the impressive centre added the extras to cut the lead to six.
They gave it their all in the final minutes but, frustratingly, well away from the Terenure line.