First the good news: Glasgow beat the defending champions away for the second successive time to claim a first win of the season and a first victory for Gregor Townsend, their new coach.

Next the bad news: scrum-half Chris Cusiter was taken to hospital with a shoulder injury which may threaten his involvement in the November internationals for Scotland.

After two near misses, Glasgow's commitment meant they fully deserved this win between the teams who had lost both their opening games. Glasgow's lineout, defence and eye for an opportunity were the decisive factors in a win where the margin was perhaps surprising but the result was not.

The left wing DTH Van Der Merwe was man-of-the-match for his two tries, but the real heroes were those up front who commanded the lineout and tackled tirelessly.

Glasgow were well short of full strength with a trio of long-term injuries and some overseas players still to land. The arrival overnight of Ava Wilson meant that her dad, Ryan, was a late withdrawal in the back row.

Nevertheless they got the perfect start as Van Der Merwe took advantage of a bit of good luck, claiming a high kick on the edge of his own 22 and shrugging off the challenge before finding himself in space with 80 yards to the line and only the prop Duncan Jones and outside-half Dan Biggar covering across. He was able to outpace both, as you would have expected, to score in the corner. Outside-half Duncan Weir missed the conversion from out wide and, more surprisingly, missed a penalty from 45 yards out but directly in front that could have given his team an early cushion.

When he did kick his first penalty, the three points were the least of Glasgow's concerns. Cusiter took a penalty quickly and was tackled under the posts, going to ground awkwardly and injuring his shoulder. It made the kick easier but the price paid was the withdrawal of Cusiter, who was helped from the pitch.

Henry Pyrgos came on and another piece of good fortune enabled Glasgow to take control of the match.

Their defence was strong and gave the Ospreys little to work with and that pressure on the home line was rewarded as scrum-half Rhys Webb fumbled at the base of a ruck. As the ball went loose and Webb complained to the referee instead of trying to make up for his error, the Glasgow flanker Chris Fusaro grabbed the ball and went over unopposed for the try, which Weir converted for a 15-0 half-time lead.

After a period of Ospreys pressure, centre Peter Horne cleared the ball and got a hard, late tackle. The visitors piled in to protect their man and the message was clear: they were not to be messed with.

The first score after half-time was crucial and Glasgow got it with a penalty. Webb deliberately obstructed play from an offside position and was sent to the sin-bin.

The Ospreys brought on the Wales internationalist and club captain Alun Wyn Jones and took kicks to the corner from penalties rather than going for goal.

Warriors' James Eddie was judged to have illegally stopped a rolling maul and he too was sent to the sin-bin. With numbers even, the Ospreys lock Ian Evans was able to charge his way over, with Biggar converting.

It response, Glasgow earned a lineout near the Ospreys line which led to another rolling maul and another player bundling his way over the line, just wide of the posts. This time it was Van Der Merwe getting his second try, thanks to confirmation from the television match official. Weir converted as Glasgow reclaimed their grip on the game. Substitute Ruaridh Jackson then added another penalty.

There were plenty of tired Glasgow legs, but the defence held as firm as it had done all evening as the brief surge of belief from the Ospreys evaporated deep into the second half.

It might not have been the prettiest of wins for Glasgow but, after their stuttering start, it was certainly one of the most welcome.