Nigeria striker Desire Oparanozie scored the only goal against a disciplined South Africa to earn her side a place in the final of the African Women's Cup of Nations against Cameroon.
South Africa started brightly but the Desiree Ellis-led side failed to capitalise on their early dominance.
Oparanozie and Ngozi Okobi both had chances to put seven-time champions Nigeria ahead in the 25th minute, but goalkeeper Andile Dlamini thwarted their shots.
Seven minutes later, South Africa had the ball in the net but it was ruled out for offside.
However, Oparanozie put Nigeria ahead with a powerful free-kick eight minutes after the restart.
Faith Ikidi was fouled in front of the South Africa box and the Guingamp forward blasted the resulting free-kick past the Banyana Banyana wall.
Wounded South Africa pressed and pushed for an equaliser forcing Nigeria to defend stoutly.
The Super Falcons almost conceded a bizarre own goal in the 83rd minute, but goalkeeper Alaba Jonathan was alert to save Ugo Njoku's awkward header on the line.
Banyana piled on the pressure and had two late chances cleared off the line, but Nigeria held on to set up a third final between Cameroon in the African Women's Cup of Nations.
The Indomitable Lionesses lost 5-0 to continental powerhouse the Super Falcons in 2004 in South Africa, while Nigeria produced a tactical performance to beat Cameroon 2-0 in the 2014 edition in Namibia.
Cameroon beat Ghana
Hosts Cameroon had earlier booked their place in the final with a 1-0 win over Ghana.
A scrappy goal on 71 minutes, when Raissa Feudijo finally scored after Njoya Ajara's effort had been cleared off the line, proved decisive.
In the first half, Cameroon's Aboudi Gabrielle Ongeune hit the post but there were few other chances.
Late in the match, they almost made it 2-0 but Michelle Ngono Mani's shot was tipped on to the bar and over.
Ghana's substitute keeper Patricia Mantey, who came on after Ama Nana Asantewa was stretchered off with a head injury, made the save but the result was already beyond the Black Queens.
The Indomitable Lionesses will take heart from their semi-final performance, having battled hard to overcome Ghana - and perhaps they might have may have won by a bigger margin.
With every seat occupied and many more fans standing in the Stade Ahmadou Ahidjo in Yaounde, Cameroon were urged on by a huge and noisy crowd.
They began brightly and on 25 minutes Ongeune used her pace down the left and what seemed like a cross turned into an effort on goal that came off the post.
Moments later there was some brave keeping from Asantewaa, who parried away a cross and then threw herself at the feet of the oncoming Cameroon attackers.
After 55 minutes Cameroon thought they had scored when Ysis Sonkeng swung the ball into the box and Michelle Akaba fired the ball into the net only for the Zambian referee Gladys Lengwe to give a foul on the keeper.
When Cameroon's goal finally came it was after a messy scramble as the Ghana keeper dropped the ball, Gaelle Eganamouit's weak shot rebounded to Ajara, whose effort was cleared off the line before Raissa Feudijo scored.
In the final minute Mani's fierce shot from the edge of the area was tipped on to the woodwork by Mantey.