In the wake of their triumph over the Scarlets, Sean Lineen’s troops had been confident of snuffing out the challenge of Ulster. But they were unable to recover fully from a disastrous spell at the end of the first half when they gave away two quick-fire tries while down to 14 men.
The opening exchanges were jittery with both sides making a spate of basic mistakes as they tried to settle. Niall O’Connor squandered an early penalty opportunity for the visitors — with Colin Gregor doing likewise at the other end. Gregor made quick amends, however, by slotting an angled effort to put the Warriors in front.
Full-back Clinton Schifcofske took over the boot duties for Ulster and was immediately on target to level the contest with plenty of mistakes still being committed.
The penalty ping-pong continued as Ulster’s Ryan Caldwell was warned for killing the ball, and Gregor confidently banged over the kick to restore the home advantage.
Schifcofske again levelled the issue, but in controversial circumstances. The offence took place inside the Ulster half, but scrum-half Paul Marshall “stole” 10 metres behind the referee’s back to make sure it was within range of his marksman.
There was a further setback for Glasgow when prop Moray Low was yellow-carded, and Ulster made the most of their extra man by creating a try on the stroke of the interval.
Their gamble in spurning a kick at the posts paid handsome dividends as flanker David Pollock plunged over, in the wake of fine link-work by Marshall and Robbie Diack.
Schifcofske added the extras, before the Warriors were floored by two more blows in stoppage time.
First, slipper Ally Kellock hobbled off injured, then Scotland winger Simon Danielli scorched in for a second Ulster touchdown in as many minutes. Schifcofske gleefully thumped over the conversion to open up a 14-point gap.
Thom Evans threw the hosts a lifeline by shrugging off four challenges to streak over in the corner, with Gregor making the touchline conversion look easy. And when substitute Dan Parks clipped over another three points the tussle was back in the melting pot.
Glasgow piled on the pressure but Parks missed a last-gasp effort to complete a night of Warriors misery.
GLASGOW: C Gregor; L Faatau, M Evans, G Morrison, T Evans; R Jackson, M McMillan; K Tckachuk, D Hall, M Low; T Barker, A Kellock; J Eddie, J Barclay, L Brown.
Replacements: D Parks for Jackson (62), B Stortoni for McMillan (57), D Turner for Barker (70), J Va’a for Eddie (34).
ULSTER: C Schifcofske; S Danielli, I Whitten, P Wallace, A Trimble; N O’Connor, P Marshall; B Young, R Best, BJ Botha; C Del Fava, R Caldwell; S Ferris, D Pollock, R Diack.
Replacements: I Humphreys for Danielli (41), M McCullough for Del Fava (72), D Roach for Ferris (41). Referee: G Morris (WRFU).