Despite poor kicking from the Warriors' out-half Pete Horne, who missed all four conversions and a penalty, the second-placed outfit impressed in open play, and were good value for their six-point victory. A bonus point for both sides leaves Ulster three points ahead of the Scots with six matches remaining.

With his squad severely depleted by injury and international call-ups, Mark Anscombe rang the changes for the Ulster starting XV to face the Warriors, handing full debuts to Neil Walsh on the wing and Conor Joyce in the back row. Among the backs, both Andrew Trimble and Paddy Wallace lined up in unfamiliar roles - centre and out-half respectively, while a new-look pack saw Callum Black, Nigel Brady, Neil McComb and Ali Birch make rare starts.

The Warriors escaped unscathed from an early Pienaar penalty attempt after collapsing a second-minute scrum, but the Springbok made no mistake on five minutes, nailing a central kick from distance as Tongan prop Ofa Fainga'anaku was pulled up again, this time for illegally killing the ball. Glasgow responded well with sustained pressure from the restart, but failed to capitalise when Horne's 11th-minute penalty fell short of the posts.

The hosts continued to press, however, and were well worth the 14th-minute overlap try touched down by second row Tim Swinson from Mark Bennett's pass. Horne's conversion effort veered wide, however, which enabled Ulster to edge back into the lead three minutes later as Pienaar kicked over from close range after Josh Strauss had illegally impeded Birch off the ball metres from the try-line.

The teams roughly shared possession and territory as the half progressed, but a mix-up at an Ulster scrum on 27 minutes, where Pienaar seemed to take his eye off the ball for long enough to allow his opposite number Nikola Matawalu in to pilfer, saw Tommy Seymour scoot into the corner for his second try of the 2012/ 13 campaign against his former province. Horne's miserable night from the boot continued, however, as his conversion again spun wide, and the score stood at Glasgow 10 Ulster 6.

Ulster offered up a spirited reaction, with several phases of rapid attack eventually forcing the Glasgow defence into another infringement on the '22'. Pienaar's kick uncharacteristically spiralled wide of the left-hand post, however, to ensure the visitors ran off four points adrift at the break.

Half-Time Score Glasgow Warriors 10 Ulster 6

The second period got off to a nightmarish start for Ulster, as Peter Murchie charged down Wallace's clearance attempt metres from the try-line, and was quickest to react as the ball dropped for the simplest of tries. Horne missed his conversion once more, but with the Warriors now overflowing with confidence, it took assiduous defending from every Ulsterman to resist the blue tide as it surged forward once again straight from the restart.

Pienaar closed the gap to six points courtesy of a 50th-minute penalty to keep his side in contention, and with Darren Cave, Paul Marshall and Rob Herring all entering the fray at this juncture, Ulster then enjoyed their best period of possession in the entire match. Frustratingly, however, they failed to register any further points during this 10-minute purple patch, which ended with the overruling of a Robbie Diack touchdown by referee Nigel Owens for a very marginal forward pass.

With the clock sitting at 65 minutes, Ulster's dominance finally translated into points with a well-executed overlap on the wing, which saw Cave find Olding wide on the right for the youngster's first senior try. Pienaar's acutely-angled conversion missed the posts, leaving the encounter hanging precariously in the balance at Glasgow 15 Ulster 14.

Man-of-the-match Matawalu proved to be the difference on 73 minutes, finishing off a move he himself had started with a flicked sideways pass to Graeme Morrison, and outpacing the Ulster defence as he retrieved the ball to ground behind the posts. Inexplicably, Horne's elementary conversion somehow screwed wide of the upright, giving Ulster a brief glimmer of hope, as a converted try would have won them the match by a solitary point.

The visitors gave it their all as the clock wound down, but as Walsh ran out of space on the right wing with only 60 seconds remaining, their faint chance evaporated into the chilly Glaswegian air, with the only consolation the losing bonus point which ensures that the league leaders go into Round 17 with a three-point lead over the Warriors.

Full-Time Score Glasgow Warriors 20 Ulster 14

Glasgow Warriors
(15 - 9) P Murchie; T Seymour, M Bennett, A Dunbar, DTH van der Merwe; P Horne, N Matawalu
(1 - 8) O Fainga'anaku, P MacArthur, E Kalman, T Swinson, T Ryder, J Strauss, J Barclay, R Wilson (c)
Replacements (16 - 23) F Brown, L Pettie, G Mountford, N Campbell, J Eddie, S Kennedy, S Wight, G Morrison

Ulster
(15 - 9) R Andrew; M Allen, A Trimble, S Olding, N Walsh; P Wallace, R Pienaar
(1 - 8) C Black, N Brady, J Afoa (c), N McComb, D Tuohy, C Joyce, A Birch, R Diack
Replacements (16 - 23) R Herring, R Lutton, A Warwick, A O'Connor, M McComish, P Marshall, D Cave, C Cochrane