EVEN with the attrition rate in modern rugby, you would have thought that five players covering one specialist role would be enough for any club, particularly when four of them are full internationalists and three were involved in the recent World Cup.

Not if you are talking about Glasgow Warriors, it would seem. They started the season with Fraser Brown and Kevin Bryce involved in Scotland's World Cup campaign.

Pat MacArthur, who has also been capped, was on duty for the club with Fergus Scott, expected to come through and challenge them. Then they picked up Shalva Mamukashvili from the Georgian, squad – and it has turned out it is still not enough.

Bryce and Scott had already gone down with shoulder problems that will keep them out for most of the season, while Brown came back from the World Cup with a toe injury that also needed surgery, though he is expected back sometime around Christmas or New Year.

Now it turns out that MacArthur broke his jaw playing against Northampton at the weekend. After surgery, he is likely to be out for about six weeks.

They can probably cope this week, when Beneton Treviso visit Scotstoun, but they have already used up their front row replacement allowance in the European Champions Cup when Mamukashvili took the spot vacated by Bryce.

Now the Georgian is the only fit registered hooker for the two December games against the Scarlets – matches they cannot afford to lose after their home defeat by Northampton.

They might be able to get away with using a prop to cover the position in the scrum, but the real difficulty is in the line out, where the ability of the hooker to hit a moving target up to 15 yards away is the difference between a set piece that works and one that misfires badly.

It is a skill that takes years to hone, and even then hookers take time to learn the styles and habits of their teammates in the drive for perfection.

For a perfect example of what happens when it goes a tiny bit wrong, check out the final two minutes of Scotland's World Cup quarter-final against Australia.

For the league, Glasgow can at least call in an Academy hooker – James Malcolm, who plays his club rugby at Ayr got the nod before Mamukashvili arrived – but Europe has its own registration process.

The rest of the team cannot afford to let it worry them, however, as they try to find the key to turning the level of performances that took them to the Guinness PRO12 title last season back on.

Glasgow know the defeat last weekend means they can't afford another if they are to make their long-promised European breakthrough, but since the World Cup players came back they have not hit their straps properly, even though they have picked up scoring bonus points in both their last two league games.

For a player like Tim Swinson, however, it represents a chance to prove that he can make a difference in one of the most competitive units in the team. While his colleagues were finding ways to win despite struggling in many aspects of play, he was sitting on the sidelines with a niggling thigh muscle problem.

When he did come off the bench against Northampton, he joined a team that was starting to win more ball and do better with it, without ever threatening to claw back the deficit.

"It is never great to lose a game; Northampton basically played the conditions better and played better as a team," he said. "You are not going to get an easy game in the Champions Cup. They are a big side, they did do really well in the physical battlers, but that is something we can work on.

"We need to get better at it. Sometimes you have a good day; sometimes a bad day, we have to make sure the bad days are few and far between."

He is likely to get his starting chance this week against Treviso, another team with a big, physical pack. "Watching them we have got to really front up in the forwards, that is where they like to play," he added. "It is an important thing to learn from our mistakes and put them right."