Golden chance is snatched away by late converted try
Once again, Ulster's season ended in bitter disappointment. And this time, the pain will be even harder to endure and get over than before.
Ulster were the better side for most of the encounter and, still, somehow contrived to lose control of this PRO12 semi-final.
They led 14-9 on 66 minutes and looked controlled and composed only for a late surge from the Warriors - who have not lost at Scotstoun since late 2013 - to snatch a place in the Kingspan final from the clutches of Rory Best and co.
This was the second successive year in which Ulster failed to make the final but rarely will they have managed to let slip a more golden opportunity.
With just five minutes to go, replacement wing DTH van der Merwe surged over in the right corner to tie the scores with Finn Russell's immensely difficult conversion bisecting the uprights to give the home side the two-point lead which they held to the end.
So, Glasgow make a second final in a row while Ulster, yet again, limp away to lick their wounds and wonder just how this one went wrong.
They led 8-6 at half-time from Chris Henry's excellent try (right) and three penalties from Ruan Pienaar - one in the first half and two in the second - seemed to have put Neil Doak's men in firm control.
But instead of closing this one out against a largely misfiring Warriors - they will wonder how they rescued it themselves - the tables suddenly turned in that last frantic five minutes to deny Ulster any chance of silverware for yet another year.
Ulster - playing into the breeze after losing the toss - got the perfect start after winning a penalty a mere few seconds after the opening whistle, which saw Iain Henderson win the ball after Ulster kicked off, with Pienaar - restored to kicking duties - slotting over the straightforward chance.
But Russell evened things up on five minutes after Roger Wilson was penalised at a breakdown. Then, after a period of stalemate, Callum Black was pinged for dropping a scrum just inside the Warriors' half and up stepped Stuart Hogg who, with the assistance of the breeze, landed a monster penalty to nudge the home side into the lead.
But Ulster then worked a wonderful try on 18 minutes when, after multiple phases, they carried hard into the Glasgow 22 through Henderson and Pienaar's pass left saw Paddy Jackson and Louis Ludik combine to work Henry free on an overlap.
The flanker dashed over unopposed, though Pienaar badly miscued the conversion attempt as Warriors skipper Alistair Kellock left the field in his final ever home game.
Leading 8-6, Ulster looked in control and continued to dominate possession and territory until a fairly serious wobble just after the half hour when Wilson and Peter Horne tangled in a rare Glasgow sortie into the 22.
This was followed, in the same move, by Craig Gilroy taking out Niko Matawalu in the air and though referee George Clancy looked at the Wilson incident, there was no card shown and the penalty against Gilroy stood.
Instead of aiming for goal, though, the Warriors went for the corner and a lineout and, not for the first time in the game, their set-piece malfunctioned and an overthrow allowed Pienaar to clear.
It was a huge moment and visibly deflated the home side though the half ended with Ludik held up over the Warriors' line but Ulster weren't able to add to their 8-6 advantage as referee Clancy gave a penalty against the visitors after a scrum collapse on the third reset.
Still, the opening 40 minutes had all been about Ulster and the dominant platform they had established in virtually every aspect of play. The only issue, of course, was that they only held a two-point lead but, now, with the wind at their backs.
The first score was critical and Ulster almost got away after Henry won a turnover only for Darren Cave's pass to Jared Payne to go to ground, which nearly saw Matawalu intercept.
But Ulster were patient and their chance came in the 56th minute after an attempted counter from deep by Russell ended in the ball going forward. From the scrum penalty, Pienaar did the needful and the first points of the half - and since Henry's try - were Ulster's to give them an 11-6 lead.
Shortly afterwards, though, Matawalu made a break and kicked ahead with Pienaar sweeping back to dot the ball down. The TMO was consulted over interference by Gilroy on the Fijian but this was dismissed and the Warriors had a five-metre scrum.
From it, they won a penalty and went for the corner only for another lineout to go awry with Henderson cleaning up. But Glasgow came again and this time Best was pinged with Russell nailing an important 61st minute penalty to narrow Ulster's lead to two.
Again, the visitors needed to respond and did when Pienaar hit a superb 66th minute penalty from out on the left not far into Glasgow territory. Ulster now led 14-9 and in a game of such small margins, this began to look crucial.
Ricky Lutton then seemed to be in trouble for holding back Matawalu but escaped a card with just a penalty going against Ulster.
Just when you thought it looked reasonably safe for Ulster, though, came a penalty in midfield which Glasgow put into the corner. You felt this was a last throw of the dice and from it the Warriors launched a huge attack.
Ulster eventually ran out of bodies out on the right when Van der Merwe ran in. That only tied the scores though and it was over to Russell to land a huge pressure kick.
The out-half nailed it and Ulster were behind with time virtually up. Four minutes remained, but Glasgow ran down the clock with Hogg missing a last minute penalty and Ulster failing to break out.
glasgow warriorS: Stuart Hogg; Tommy Seymour, Richie Vernon, Peter Horne, Niko Matawalu, Finn Russell, Henry Pyrgos; Ryan Grant, Fraser Brown, Rossouw de Klerk, Jonny Gray, Alastair Kellock (capt), Josh Strauss, Chris Fusaro, Adam Ashe.
Replacements: Pat MacArthur, Gordon Reid, Mike Cusack, Leone Nakawara, Ryan Wilson, Duncan Weir, Sean Lamont, DTH van der Merwe
ULSTER: Louis Ludik; Tommy Bowe, Jared Payne, Darren Cave, Craig Gilroy, Paddy Jackson, Ruan Pienaar; Callum Black, Rory Best (capt), Ricky Lutton, Lewis Stevenson, Dan Tuohy, Iain Henderson, Chris Henry, Roger Wilson.
Replacements: Rob Herring, Andrew Warwick, Bronson Ross, Robbie Diack, Sean Reidy, Paul Marshall, Stuart McCloskey, Michael Allen.
Match rating: 6/10
Man of the match: Finn Russell (above). Held his nerve right at the death to break Ulster hearts and send Glasgow to a final in Belfast.