Temba Bavuma has no doubt over the talent of Kwena Maphaka and says the fast bowler is "not on trial" when he makes history for South Africa on Friday.

Maphaka is preparing to make his Test debut against Pakistan, aged just 18 years and 270 days on the opening day of the second red-ball clash.

That is set to make Maphaka the youngest Test debutant for South Africa at Newlands, where he will feature with just three first-class outings to his name.

"Kwena selection is on potential, more than anything. But obviously, he exudes talent and we wanted to go with an extra bit of pace as well," Proteas captain Bavuma said.

"We're quite excited for Kwena. Also considering the fact that we've got a series on the line, we want to give an opportunity to a young guy, when there's a consequence to it.

"Whatever happens from his point of view, from a performance point of view, it'll put him in good stead."

Maphaka already caught the eye in the ODI series against Pakistan, featuring twice and taking five wickets, including 4-72 in the third clash.

"With a guy like Kwena, you want to allow him to be as free as he can," Bavuma added. "You want to allow him to continue being the Kwena he is and to allow the exuberance of youth to come out.

"More specifically with him, it's a case of Kwena running and bowling as quickly as you can, allowing him to kind of just spread his wings. Obviously with him, he doesn't have the foundation.

"A lot of us played first-class cricket, we were able to fail, come back and find a way. He's just going to have to learn quite quickly but he has the talent that will make it a little bit easier for him.

"Also, he's not on trial in this game. We know what his talent is about."

Maphaka was brought into the Test squad for the Sri Lanka series last month but did not play, despite injuries to Gerald Coetzee and Wiaan Mulder.

Dane Paterson managed 13 wickets across his last two Tests, but he has made way for the record-breaking 18-year-old.

Bavuma is yet to share the Test stage with Maphaka, but they have already played in ODIs together, and he hinted at the bowler sharing the new ball with Kagiso Rabada.

"I'm sure he'll be looking forward to running in with KG over the next five days," Bavuma said. "We're super excited for the young talent.

"He seems like he wants to be the man for the team. He has the characteristics to at least to fulfill his potential. I guess for us it's to support him and make him feel free to continue being the person that he is."