Auckland - England and South Africa will meet in the final of the IRB Junior World Championships winning contrasting semi-finals on Sunday.
Defending champion England scored five tries to trounce Ireland 42-15 while 2012 champions South Africa needed a 78th-minute try to edge four-time champions New Zealand 32-25.
Hooker Corniel Els scored the decisive try Sunday for the Baby Boks, who also beat New Zealand 33-24 in pool play.
Their clash provided a contrast in styles between the running game of the New Zealanders and the more measured, kicking game of the Baby Boks who also depended on the work of their giant forward pack.
New Zealand matched them in the scrums and played more attractive rugby but was beaten by a side that ground away relentlessly for 80 minutes.
Flyhalf and captain Handré Pollard played a decisive role for South Africa, scoring a try and kicking three conversions and two penalties for 17 points.
Pollard guided South Africa around the field with a powerful boot and was able to secure possession in a vigorously physical contest.
He scored South Africa's opening try, converted tries by Sergeal Petersen and Els but missed the conversion of a 70th-minute try to center Andre Esterhuizen.
New Zealand was the more skillful side and played some outstanding attacking rugby, much of which was sparked by fullback Damian McKenzie.
But their play was high-risk and they missed a number of tryscoring opportunities through errors.
The New Zealanders scored three tries but as many went begging as they tried to force the pace of the game and attack even from deep within their territory.
England scored four first-half tries to take control of their semifinal against Ireland.
Harry Sloan, Danny Hobbs-Awoyemi, Howard Packman and Tom Woolstencroft all touched down as England took a 34-3 lead at halftime.
Ireland played with tremendous spirit to close the gap in the second half, scoring tries through Garry Ringrose and Alex Wootton.
The final will be played on Friday while New Zealand and Ireland will playoff for third and Australia and France will contest fifth place.