THIS was an ugly win, seized at the death after a scrappy and often error-strewn performance, but it is a scalp to cherish.

Glasgow knocked Munster off the top of the Guinness PRO12 table with victory over the Irish side at Scotstoun yesterday, breathing new life into their own season in the process. The Warriors have won games with more style this season, but they have taken few more valuable points.

Trailing with eight minutes remaining, Glasgow were staring at a defeat that would have been hard to come back from over the weeks and months ahead. But a stirring run by DTH van der Merwe took them deep into the Munster 22, and they re-secured possession efficiently at the resultant scrum.

From there, they laid siege to the Munster line with a ruck on the left side of the pitch, and it all ended with Jonny Gray, deservedly named man of the match, thrusting himself over for the try that tilted the match their way.

Relief, then, for the supporters, but neither the players nor the coaches will reflect with great satisfaction on what happened up to that point. Sure, Munster made life hard for the home side, but Glasgow didn't exactly help their own cause as they failed to manage their territory and, most damagingly, struggled to lift pressure on the few occasions the Irish team applied it.

As you might expect of a team that had made 10 changes, Glasgow seemed to be suffering no great European hangover after their loss to Toulouse last weekend. However, if there was a spring in their step during the first half, there wasn't a lot of continuity. Three penalties from Finn Russell put them into a 9-8 lead after half-an-hour, but after every one of them their failure to wrap up the restart put them under pressure in their own 22.

The most damaging passage had been in the eighth minute. Russell opened the scoring moments earlier when he punished Munster's scrum collapse by claiming the first three points of the game, but Glasgow promptly spilled the ball in the shadow of their posts. Munster then showed all the composure Glasgow seemed to lack in the first half, working the ball through a couple of phases before sending JJ Hanrahan through a gap between Josh Strauss and Leone Nakarawa, although Hanrahan missed the conversion.

Glasgow probably had more chances to make things happen at the other end of the pitch, but at the end of the first half it was fiendishly difficult to recall a moment when they were within striking distance of the line.

The closest they came was in the 16th minute when they hammered away at the Munster defence with some lovely phase play. However, the loveliness evaporated when Russell knocked on five yards short and Munster cleared the danger.

Glasgow wasted an even better opportunity a few minutes later when Munster were reduced to 14 men by the yellow card shown to Paul O'Connell. The loss of their captain and talisman should have reduced Munster significantly, but Glasgow took no real advantage. Russell did clip over one penalty, but Hanrahan cancelled it out with another of his own.

Munster wound down the clock as best - and as blatantly - as they could while they were missing O'Connell. That frustrated the Glasgow fans, and the players seemed just as uncomfortable.Restored to full strength, Munster upped their already impressive workrate and put the pressure back on Glasgow. It seemed the Warriors were going to take a one-point lead into the break, but it became a two-point deficit in the 38th minute when Hanrahan added another penalty.

And then disastrously, in the final play of the half, Glasgow again failed to mop up Munster's danger, turned the ball over yet again, and coughed up another try when a sequence of forward charges ended with No 8 Robin Copeland crashing over for Munster's second try.

Hanrahan's conversion gave Munster an 18-9 interval advantage. More significantly, it obliged Glasgow to open up and chase the game, which is pretty much what they did in the third quarter. For a few minutes it seemed their urgency might be their undoing, as they made errors going for over-ambitious passes and spaces that simply did not exist, but the breakthrough arrived in the 52nd minute when Nakarawa stretched over for a try after some strong build-up work by Strauss and Gray.

Physically, Glasgow were more than a match for Munster up front, but that seemed lost on referee Leighton Hodges as he penalised the Warriors in a scrum they appeared to be dominating. Yet Hodges could hardly be blamed for Glasgow becoming bogged down in their own half after Nakarawa's try, for the players themselves were entirely at fault for that as they turned over possession far too easily and gave Munster soft chances.

Fortunately, Munster were slow to take advantage. Hanrahan had a couple of wild misses with penalty attempts that brought hoots of derision from the Scotstoun stands, but there were just as many - if not more - groans as Glasgow's errors stacked up.

Yet just as their fans began to fear the worst, Glasgow summoned reserves of energy for one last assault. Van der Merwe worked his magic through the middle of the field and the forwards did the rest to help Gray over the line.