Scotland are preparing to juggle their locks over the weekend, depending on whether Scott Murray, the country’s record cap-holder, becomes available for the tour to Argentina after playing for his French club tonight. With seeding for the World Cup at stake, Frank Hadden, the head coach, is prepared to pull out all the stops to send the best possible squad to South America, and though Murray has hardly featured since the last World Cup, his experience means he would be an invaluable asset.

When the Scotland party flies out to Argentina this evening, it will include Craig Hamilton, the Edinburgh lock who won five caps in 2004 and 2005. If Murray does become available, then Hamilton will make a quick about-turn in Buenos Aires and head north to join the Scotland A team that is taking part in the Churchill Cup in Canada.

Whatever happens, the uncertainty is going to be tough for Hamilton, who potentially could find himself arriving in Canada on Monday and playing the following day, but Hadden was full of praise for the way the player has handled the position. “Craig has been the consummate professional in this situation and I thank him for his first-class response,” the coach said.

The confusion has arisen because Murray has been told by Montauban, his club, that they are prepared to release him for Scotland duty but only after they have clinched a place in next season’s Heineken Cup. They still need one more win to be mathematically certain of the all-important seventh place in the Top 14 and could secure that this evening when they are at home to Clermont Auvergne.

Normally, you would look at the gulf between the sides - Clermont are runaway leaders in the competition and hammered Montauban 40-13 in the reverse fixture – and assume it is at best a long shot. However, Clermont, who have already qualified for the play-offs, are taking the chance to rest most of their leading players and Murray and his teammates will be facing a makeshift team with a lot of fringe players getting a rare outing.

A club such as Clermont have plenty of strength in depth, and are also using the game to bring back a couple of leading players who have recovered from long-term injuries to get them ready for the play-offs, but Montauban have lost at home only once in the league this season – 16-12 against a full-strength Toulouse side – and feel capable of springing an upset.

If they manage it, and stick to their promise, that would free Murray to travel to Argentina, where he would be likely to add to the 87 caps he has already won. While Scott MacLeod would appear to be an automatic choice, it is harder to work out who would join him because Matt Must-chin is not only uncapped but had his first experience of international training only this week, and Alastair Kellock has not played since damaging his knee in February.

Kellock was the other addition to the squad yesterday, but that decision was close to automatic as soon as he had proved his fitness after keyhole surgery on the knee that locked up playing against the Ospreys at Firhill.

While the players see the tour as a chance to pick off a big scalp against the nation ranked third in the world, there is also a bigger picture to consider with the seeding for the 2011 World Cup depending on world rankings in December this year.

Scotland are currently tenth, which would put them in the third band of nations and mean they would have to beat a side ranked above them to reach the World Cup quarter-finals, but if they can win both games against Argentina, or win one by more than 15 points and keep the score close in the other, and if neither Ireland nor Fiji, the teams immediately ahead of them, spring any surprises, they could rise to eighth and move up a seeding bracket.

With so much to play for, Hadden feels he has no option other than to try his best to get the strongest possible side on to the pitch, even if that means delaying the decision on Murray and Hamilton.