Glasgow 17 Ulster 20
Ulster produced a stirring fightback today to claim safe passage to a Celtic League semi-final showdown with Munster in Limerick.
Glasgow had appeared to be in the driving seat at Hughenden thanks to a string of great kicks by Tommy Hayes.
But the former European champions snatched the glory with a try by Andy Ward - while Hayes failed when it really mattered with two late penalty misses.
The Scots raced off to a bright start, breaking the deadlock with less than three minutes on the clock with a Hayes penalty.
But Ulster weathered added pressure to square the issue with a well-struck David Humphreys penalty from almost 50 metres.
The province suffered a setback in the 25th minute as hooker Matt Sexton limped off to be replaced by Paul Shields.
But the change did not upset their rhythm and only a last-gasp tackle by Jon Steel on Scott Young prevented a touchdown in the wake of a sizzling move featuring Neil McMillan and Humphreys.
Glasgow's relief lasted only a minute, however. With their next attack, scrum-half Neil Doak caught the home markers flat-footed before freeing Jonny Bell.
Although the centre was floored a metre short of the target, he had enough power to bounce his way across the line - giving Humphreys a simple conversion.
Hayes instantly banged over his second penalty to repair some of the damage - and even better was to come for the Warriors almost on the break.
With the referee playing a long advantage, Glenn Metcalfe burst into the game to set up the platform - and it was Steel who was left with a cruise to the line after a slick sequence also starring Gordon Bulloch and Calvin Howarth.
Hayes was wide with the kick - but still had time to make amends by completing his penalty treble.
And he repeated the dose shortly after the restart to open up a seven-point gap.
Glasgow continued to hold territorial advantage - only to be rocked by a sucker punch involving Ryan Constable and Ward.
Constable did the initial damage with a super surge into enemy territory. With the home defence out of position, the ball was quickly recycled to Ward, who only had to flop across the line.
The conversion was from an awkward angle, but Humphreys sent it through to tie up the scores and set up a dramatic finale.
And the flags of the large Ulster following were waving again five minutes later as Humphreys stunned the Warriors yet again with a long-range penalty.