Glasgow (6) 13
Drop Goals: Parks
Ulster (8) 20
Pens: Larkin 4.
Drop Goals: Larkin.
Ulster claimed a deserved place in the Celtic Cup final by holding off Glasgow's challenge in Friday evening's clash at Hughendun.
After being a tad fortunate to lead 8-6 at the interval, Ulster then took control to extend their advange to 11 points going into the closing stages.
Graeme Morrison's converted try two minutes from time then strained Ulster nerves but Adam Larkin's injury-time penalty made the game safe for the visitors.
Ulster had an early try-scoring chance but full-back Bryn Cunningham elected to cut inside when a pass to the overlapping James Topping seemed the better option.
However after a scrappy 10-minute period, Ulster did notch the opening try of the match with Ryan Constable superbly holding off two attempted tackles to score in the corner after Andy Ward had successfully chased his own kick out of defence.
In response, Glasgow then produced 15 minutes of sustained pressure with Ulster's play not been helped by a succession of lost line-outs.
Spurred by some tremendous defensive play from captain Ward, the visitors held firm but a high tackle from Ulster centre Paul Steinmetz presented a penalty chance for Daniel Parks in the 26th minute and the Australian native made no mistake.
Ulster replied four minutes later with Adam Larkin slotting a 35-metre penalty but Parks almost immediately left only two points between the sides again by slotting a delightful drop goal.
Glasgow found it difficult to break down Ulster
On the stroke of half-time, Ulster suffered a blow when Irish U21 international Matt McCullough was forced to leave the field with what appeared to be an ankle injury. Rowan Frost was introduced as a replacement.
Ulster coach Alan Solomons, clearly not happy with his side's first half display, made three further changes at the break with prop Simon Best, scrum-half Neil Doak and Roger Wilson introduced for Bryan Young, Kieran Campbell and Tony McWhirter.
The changes spurred the visitors into a lively start to the second half with a Glasgow offside yielding a penalty which was scored by Larkin.
Glasgow's prospects then weren't helped by Andy Hall's sinbinning for a blatant offside offence.
Ulster missed a great chance to add to their lead in the 55th minute when Andy Ward lost possession in the tackle only a yard short of the Glasgow line.
Despite the Ulster domination, they were finding scores hard to come by.
However, Adam Larkin duly delivered a crucial score in the 75th minute when he hit a fine penalty from a difficult angle just outside the Glasgow '22.
With Ulster now 11 points ahead, the game seemed over.
But Glasgow then notched a try against the run of play when Doak's clearance was charged down and Graeme Morrison punished the error.
Substitute Calvin Howarth's conversion left only four points between the teams but Ulster maintained their composure and Larkin's fourth penalty of the night made the game safe.
Ulster will meet the winners of Saturday's second semi-final between Connacht and Edinburgh in the decider.
Glasgow: R Kerr, D Millard, G Maclure, G Morrison, S Lamont, D Parks, S Pinder, M Proudfoot, S Lawson, L Harrison, A Hall, N Ross, C Mather (captain), D Macfadyen, P Dearlove.
Replacements: S Gunn, A Kelly, J Beardshaw, R Reid, M McMillan, C Howarth, J Steel.
Ulster: B Cunningham, J Topping, R Constable, P Steinmetz, T Howe, A Larkin, K Campbell; B Young, M Sexton, R Moore, M Mustchin, M McCullough, A Ward, N Best, T McWhirter.
Replacements: P Shields, S Best, R Frost, R Wilson, N Doak, S Stewart, S Young.