Springbok front rowers Schalk Brits and Marcel van der Merwe have both been ruled out of the end-of-year tour with a knee injury.

Van der Merwe had been scheduled to join up with the Boks in Stellenbosch this week, but suffered a blow during the closing stages of the Blue Bulls' Currie Cup semi-final defeat to Western Province on Saturday. He has subsequently been ruled out of action for up to six weeks.

'He fell awkwardly in the last few minutes of the game,' Bulls doctor Org Strauss told SuperSport.com. 'He has a grade two medial ligament tear, luckily not the same knee that has given him problems in the past, I expect him to be out for anywhere between four and six weeks.'

Brits was ruled out earlier in the day after suffering a knee injury while playing for Saracens in the European Champions Cup at the weekend. Saracens head of medicine Joe Collins has confirmed the hooker will undergo surgery on Tuesday. While no timeline has been given, Brits could miss the remainder of the European season.

It's the absence of Van der Merwe, though, that will be the biggest blow to Heyneke Meyer's plans. With so few quality tightheads in South Africa at present, the matches against Ireland, England and Wales would've provided the Bok coach with the perfect opportunity to test Van der Merwe's international credentials in similar conditions that will be experienced during next year's World Cup.

Sharks front rower, Lourens Adriaanse, was called up to the squad on Sunday and has been part of the set-up before, while the Golden Lions duo of Julian Redelinghuys and Ruan Dreyer must also be considered as candidates for the role of Jannie du Plessis's understudy. Both have been impressive during the Lions' run to the Currie Cup final, while Redelinghuys showed himself capable at a higher level during the Lions' Super Rugby campaign.

Photo: Ashley Vlotman/Gallo Images