Jean Lonergan and Marie Barrett come back into the front row, Rosie Foley is named at lock and Suzanne Fleming takes a spot on the wing.
Irish captain Sarahjane Belton has been moved to fullback in a direct swap with Joanne O Sullivan.
Ulster prop Gillian McAllister loses out from the match squad completely as does winger Amanda Greensmith and scrum-half Louise Beamish.
Onto the bench comes Mairead Kelly and Laura Guest for their first appearances at this tournament.
For the first time in the competition Ireland head into a game as favourites as the South Africans have suffered huge defeats at the hands of Australia and England shipping more than 140 points in the process.
A victory would provide a huge boost to Ireland as they head into the final weeks of the competition with only two likely games remaining after tonight s match.
The changes to the Irish team, while not entirely unexpected, could help Ireland attack from every opportunity with skipper Sarahjane Belton reverting to her former role in the number 15 shirt and being joined back there by Suzanne Fleming - who captained Ireland at their last World Cup.
Their experience coupled with the ability of both players going forward and the pace of Jeannette Feighery on the other wing could see Ireland make serious inroads on the counter.
Today is the last day of the pool games at the competition with seven teams still in contention to claim an all-important top four spot and a shot at the title.
Two of the unbeaten teams - New Zealand and Scotland - face each other at Ellerslie Rugby Park.
The other two undefeated sides - England and France - meet in the final game at St Albert Rugby Club, knowing that defeat could see them lose out on a top four place.
Canada, who recovered from an opening day defeat to New Zealand when they outclassed Spain 79-0, will be looking for a bonus point victory over Kazakhstan.
The USA and Australia play each other at St Albert, knowing victory and favourable results elsewhere could see them sneak into the top four. Samoa face Spain in the other game of the day.
Ireland team to play South Africa, St. Albert Rugby Football Club, Edmonton, tonight 7pm (Irish time):
F Coghlan, J Lonergan, M Barrett, C Mahon, R Foley, O Brennan, R Boyd, J Neville, T Rosser, J O'Sullivan, S Fleming, G Davitt, L Cantwell, J Feighery, SJ Belton (c)
Replacements: Y Nolan, L Guest, G Healy, E O'Sullivan, M Kelly, N Ni Chadhain, S Houston
IWRFU Press Officer