Depleted Super Rugby semi-finalists the Stormers have signed Schalk Brits on loan from English club Saracens, before promising not to play him in his familiar hooker position.

The former Springbok will be among the seven replacements for a showdown with seven-time Super championship title holders the Crusaders at Newlands in Cape Town on Saturday.

But coach Allister Coetzee stressed that Brits would come on as an "impact player" and not as a hooker because this was a condition of the loan being approved by competition organisers SANZAR.

"We will use him only as a loose forward. I view the role of the players on the bench as important - they are not there just to come on if a team-mate is injured," Coetzee told reporters.

"Schalk has similar attributes to our loose forwards and if you saw him play for Saracens, the role he filled when coming on was similar to that of a flanker."

Injuries have ruled out No.8 Duane Vermeulen and flank Pieter Louw and the weekend mugging in the south-west city of young reserve loose forward Siya Kolisi was the last straw.

"Siya was the victim of an unfortunate incident in which he was mugged and sustained injuries to his head and concussion and cannot be considered for the semi-final," said Coetzee.

Normal back-up loose forward Nick Koster is expected to replace Springbok 2011 Rugby World Cup candidate Vermeulen for a match that will attract a sell-out 45,000 crowd to the Test venue.

Crusaders, who qualified for the semi-finals with a 36-8 home victory over the Sharks last Saturday, will be able to field a much stronger side than that which defeated the Stormers by six points in Cape Town a month ago.

Captain and flanker Richie McCaw, locks Sam Whitelock and Brad Thorn, fly-half Dan Carter and scrum-half Andy Ellis missed that game through injury and wing Sean Maitland and fullback Israel Dagg had to retire hurt before halftime.

Replacement fullback Adam Whitelock and stand-in scrum-half Kahn Fotuali'i also had to leave the field during the first half of a bruising battle settled by two tries from prop Wyatt Crockett.

All except long-term casualty Dagg will be available for the Crusaders and the other semi-final will be staged earlier on Saturday in Brisbane between the Queensland Reds and Auckland Blues.

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