South Africa produced a clinical display of forward power to secure a bonus point by scoring five tries and with it, a place in the semi finals. Earlier, New Zealand outclassed England 34-13 at Ravenhill to finish top of Division A. The result means England can finish fifth at best.
Defending champions Australia produced a powerful second half performance against France to secure their semi final place with a 30-11 win. France can now finish no higher than fifth.
The surprise team in the top four is Wales, who enjoyed a 29-0 victory over Argentina.
Samoa recorded their first win of the tournament, defeating Japan 28-12 at Deramore Park, the home of Belfast Harlequins, while Fiji grabbed a shock 25-23 victory over Scotland at Shaw's Bridge.
IRB U-19 WORLD CHAMPIONSHIP - DIVISION A DAY THREE RESULTS:
Scotland 23 Fiji 25, Shaw's Bridge
New Zealand 34 England 13, Ravenhill
Samoa 28 Japan 12, Belfast Harlequins
Argentina 0 Wales 29, Shaw's Bridge
Australia 30 France 11, Belfast Harlequins
South Africa 31 Ireland 5, Ravenhill
DIVISION A PLAY-OFF FIXTURES:
- Tuesday, April 17 -
10th-11th Play-Off - Fiji v Scotland, Belfast Harlequins, 5.30pm
9th-12th Play-Off - Ireland v Japan, Shaw's Bridge, 7.30pm
6th-7th Play-Off - England v Argentina, Shaw's Bridge, 5.30pm
5th-8th Play-Off - France v Samoa, Belfast Harlequins, 7.30pm
2nd-3rd Play-Off - Australia v South Africa, Ravenhill, 5.30pm
1st-4th Play-Off - New Zealand v Wales, Ravenhill, 7.30pm