Facing a full-blown injury crisis that seems to have grown by the day, Scotland head coach Scott Johnson has postponed naming his team to face South Africa in Nelspruit on Saturday to allow a number of players to undergo fitness tests.

The area of most pressing concern is the front row. Ryan Grant's call-up to the Lions on Friday took one prop out of the equation and another was removed yesterday when Geoff Cross was ruled out of the remainder of the Castle Lager Test Series by the shoulder injury he sustained in the 27-17 loss to Samoa in Durban last weekend.

Euan Murray suffered a hamstring injury in that game as well, and he is currently under observation. Even if he is cleared to play, Scotland now have just four fit props, the absolute minimum needed for a Test match under current international rules.

Their resources have been bolstered by the arrival of Jon Welsh as cover for Grant, but they still look dangerously thin. With no further additions to the squad they would have no room to maneuver, and they would be left exposed if any one of the props took a knock in training.

The situation is little better at hooker. Pat MacArthur, whose Test debut against Samoa lasted just 10 minutes until it was ended by a knee injury, is expected to fly back to Scotland today, and as yet no replacement has been called in. As things stand, Scott Lawson and Steve Lawrie are the only fit hookers in the squad.

Dougie Hall could be a candidate to replace MacArthur, but his fitness situation is unclear at the moment. None of the other hookers at Edinburgh and Glasgow has accumulated the quality or quantity of experience that would qualify them to take part in a full Test against a South African side which is currently rated the second-best team in the world.

Beyond the front row, a number of other players are still causing concern. Squad captain Kelly Brown, who sustained an ankle injury against Samoa, underwent a scan in Nelspruit yesterday and is expected to be the subject of further assessment over the next 48 hours. Johnnie Beattie, who picked up a shoulder injury, and Tom Heathcote and Alex Dunbar, who both suffered concussion, will also have to convince the Scotland medical staff of their fitness ahead of Thursday's selection decisions.

The silver lining to the cloud that descended over the squad's training base, a few miles north of Nelspruit, was provided by Welsh, who won a first cap against Italy last year but then suffered a serious shoulder injury in training on Scotland's Australasian tour and was out of action for seven months.

"It's great to be called up to a place like South Africa to represent your country," said Welsh. "The Springboks are one of the best scrummaging sides in the world, but it's a challenge I would relish. My head is switched on and I'm ready to go."