Cape Town - Springbok scrum coach Pieter de Villiers is happy with South Africa's depth in the critical position of tighthead prop.After being humiliated by the Argentine scrum earlier in the Rugby Championship, the Bok front row responded well in subsequent away Tests against Australia and New Zealand.Jannie du Plessis started at tighthead on both occasions and his replacement - Marcel van der Merwe - did well when he came on.Late in the Test against the All Blacks in Wellington, the Boks turned over possession after a powerful scrum which gave them a shot at sneaking a victory. They lost 14-10 but have taken a lot of confidence from the way they put the All Black scrum under pressure. Van der Merwe and Trevor Nyakane (who replaced loosehead Tendai Mtawarira) were the two Bok props doing duty at the time.De Villiers told Die Burger that he's happy with the way things have improved in the front row, especially at tighthead."Jannie continues to perform very well, while Marcel made a difference when he came on near the end of the game against the All Blacks," said De Villiers."Frans Malherbe is not available due to injury but has already proven that he has a bright future."The Boks tackle the Wallabies at Newlands on Saturday (17:05 kick-off).