Glasgow 13 Ulster 20
Glasgow's bid to earn Celtic Cup semi-final revenge were dashed by the streetwise Irishmen at Hughenden.
The Warriors were aiming to make amends for last season's defeat by the same opponents but again they could not find the firepower when it mattered.
Australian centre Ryan Constable sparked the victory with a superb first try, leaving Adam Larkin to make sure of the win with a series of kicks.
Dan Parks opened Glasgow's account with a penalty, but it was Ulster who reacted more positively and they quickly restored their advantage thanks to an identical score by Adam Larkin after Glasgow crept offside.
The end-to-end action continued in the build-up to the interval and the Warriors hit back with a slick drop-goal by Parks at the end of a sustained spell of phase-play.
Ulster suffered a major setback in stoppage time when lock Matt McCullough was stretchered off with a serious-looking ankle injury.
They made a spate of substitutions at the restart and stepped up the pace in the opening stages of the second half.
Larkin slotted another penalty from close-range after Glasgow failed to roll clear in the wake of a tackle.
Welsh referee Huw Watkins incurred the wrath of the home fans in the 6,000 crowd again five minutes later.
First, he penalised Andy Hall for charging offside at a ruck when the ball appeared to be out and free to be played. And to increase Glasgow's frustrations, he then ordered Hall to the sin-bin.
They enjoyed a reprieve as Larkin was off-target with a penalty from 50 metres. But he rediscovered his touch six minutes from time from an awkward angle.
Larkin then clipped over an opportunist drop-goal to give Ulster an 11-point cushion.
Only then did Glasgow find the key to unlock the defence with a Graeme Morrison try, goaled by sub Calvin Howarth.
But it was too late to turn the tide, and Larkin had the last word with penalty number four.