The Stormers say influential loose forwards Duane Vermeulen and Rynhardt Elstadt are returning home from Australia on Monday after both sustained knee ligament injuries in their Super Rugby loss to the NSW Waratahs in Sydney.

Coach Allister Coetzee said the pair would be out for between six to eight weeks with medial ligament problems in a “massive blow” for the Cape Town-based team.

No.8 Vermeulen’s injury also puts him in doubt for the Springboks’ June internationals, with Scotland, Italy and Samoa set to visit South Africa for a four-nation tournament next month.

Inexperienced forward Gerbrandt Grobler has been called up by the Stormers for their final game on tour against the Melbourne Rebels on Friday.

The Stormers, semi-finalists last season, are 10th out of 15 teams in 2013 with four wins and six losses.