In theatrical circles they say the perfect dress rehearsal foretells an error-strewn first night, and maybe that dictum can now be applied in the sphere of sport as well.

Glasgow did precious little wrong in their easy win over Exeter at Sandy Park last weekend, but they certainly made up for it at Scotstoun on Friday, when they needed a final-quarter moment of magic from Tommy Seymour to see themselves past a doughty, but limited, Cardiff Blues side.

In fairness, there was more than the distance between Glasgow and Devon to separate the two games. The Exeter exercise was a romp in early autumn - or maybe they call it late summer down there - sunshine, while the Glasgow game was a grim grind of an affair, played in teeming rain throughout.

In which light (or lack of it), Seymour's spearing run to collect his try in the right corner was a welcome moment of brilliance, and not just for those sodden spectators in that part of the ground.

Expectations around Glasgow have been so high in recent months that a fall at the first hurdle of the new RaboDirect PRO12 campaign would have been a particularly bitter pill to swallow and a more crushing experience than any opening defeat in seasons past.

Seymour mopped up the plaudits after the 22-15 win, but the urgency that came into Glasgow's game towards the end had as much to do with the arrival of the new half-back pairing of Chris Cusiter and Ruaridh Jackson just a minute before the touchdown. Jackson played with all the assurance that had been missing from the unfortunate Scott Wight's performance, while Cusiter's display was a heartening reminder of just how good a player he is.

With so many injury absences in recent seasons, Cusiter is like one of those 10-year-old cars that has only done 15,000 miles. Given that his courageous style of play veers towards recklessness at times you would hesitate to stick the "one careful owner" sticker on the windscreen, but there is little doubt that he has many miles left on the clock yet.

Cusiter's appetite is all the more remarkable after two season-long injuries that would sap the spirits of even the most resilient of players.

"There were dark days when I thought it was never going to sort itself out," he said of the shoulder problem that virtually wiped out his 2012-13 campaign. "I was doing day after day and month after month of rehab and nothing was happening."

Crueller still, Cusiter suffered a relapse when he returned to training last March. "Hurting it again and going back to square one - that was really tough to handle," he said. "You can't help but think: what's the point?"

Cusiter is a bit small to be Glasgow's main enforcer, but his relish for rugby returned during his comeback cameo against Exeter as he dished out a bit of punishment to a player who was lying on the wrong side of a ruck. "It really brought back the enjoyment," he said. "I absolutely loved it. I thought: That's why I've been through what I've been through. Then against Cardiff, just playing with my team-mates in a good win - being part of it was just so good. That's what I missed."

Tomorrow's debrief might not be such an enjoyable experience for Cusiter and his chums. Yet it is easy to suspect that coach Gregor Townsend is quietly satisfied with the fact he has a busy week ahead, but not one he had to pay for with a defeat.

Neither, in all likelihood, with a serious injury. Captain Al Kellock was carried off on a stretcher after just 20 minutes, but the indications from within the Glasgow camp yesterday were that the problem is not as bad as first feared.