Assistant coach Mzwandile Stick has backed 23-year-old flanker Paul de Villiers to step up in Siya Kolisi's absence when the Springboks face New Zealand in the first Rugby Championship Test at Ellis Park on Saturday.

Kolisi has been held back from the squad to protect his availability for the remainder of the four-match series, with De Villiers — who made his Test debut against England last month — retaining the No 6 jersey. The Stormers loose forward started all three Nations Championship matches in July against England, Scotland and Wales.

"Not having Siya will always be a big loss for us," Stick said at the pre-match press conference. "But the trust that we've shown in De Villiers, from the beginning against big teams, gave him an opportunity and then everyone is talking about him."

Stick pointed to De Villiers' breakdown work and ball-carrying as his standout attributes, and was particularly struck by the maturity the youngster has shown. "He understands his role very well in the team and we always say, irrespective of your age, if you take full ownership of what needs to be done in the team, you are also a leader."

The Springbok management identified De Villiers' leadership potential early — he captained the Junior Springboks — and Stick said those qualities have translated seamlessly to Test level. "He didn't stand back for anyone. I know a lot of people focus on his breakdown skills, but the way he's been carrying, he doesn't stand back for anyone."

De Villiers lines up against an All Blacks loose trio of Tupou Vaa'l, Luke Jacobson and Ardie Savea, with Pieter-Steph du Toit — captaining the side in Kolisi's absence — and Jasper Wiese alongside him.

Du Toit, set to earn his 99th Test cap, was equally effusive. "Probably one of his strengths is his fitness. He's a very fit guy and has good speed as well and very strong, especially when he's over the ball. He's very comfortable in his body, in his position, who he is as a person and who he is in the Springbok team."

Du Toit also flagged the areas where the Boks expect New Zealand to test them. "We know New Zealand is going to bring intensity and we really believe the lineouts and the scrum is going to be something where we're going to have to perform well. They're quite fast and really skilful players so they're definitely going to try and exploit us."

Kickoff at Ellis Park is at 5.10pm.