Powell said the team must close out games in the last minutes of matches, not concede tries.
"We need to make a step-up in that regard, especially tomorrow when we are in the knock-out stages of the tournament. We have slipped up in knocking teams out of the Cup. We did that in Cape Town against New Zealand and again today against Australia. This has an impact on the overall standings on the log on the long run."
The Blitzboks had some misfortune in their opening match when Philip Snyman clashed heads with a Tongan opponent. He sustained a gash on the cheek and was ruled out of play for the rest of the day.
“Philip had a bit of a headache afterwards and we decided to give him a rest. He will be tested again in the morning. If he is fit, he will play, if not, Kyle Brown will replace him,” Powell said.
Tonga scored first in the match when Fine Inisi finished off a long range effort after just two minutes. The Blitzboks regrouped quickly with tries by Werner Kok and Siviwe Soyizwapi, both converted by Branco du Preez for a 14-5 lead at the break.
The second half was much more pleasing on the eye for Blitzboks supporters as Kok and Soyizwapi grabbed a second each, as did Stedman Gans. Dewald Human grabbed a late try and kicked two conversions. Selvyn Davids kicked one conversion.
Against Argentina, the Blitzboks again trailed in the first half. Renzo Barbier scored for the South Americans before Soyizwapi ran hard for his first five pointer of the match. Scores were tied 5-5 at the break.
The second half saw Soyizwapi scoring his second before Selvyn Davids ran 80 meters to finish a counter attack. Argentina came back with a try by Rodrigo Etchart, but Justin Geduld and Gans both ran in for the win. As Argentina earlier in the day overcame Australia, the match against the Blitzboks was a must-win for the defending champions. They needed to win by five points or more to stay in the Cup. A great start raced them to a 17-0 lead in the first four minutes following tries by Jeral Skelton and Lewis Holland (2).
Geduld pulled one back just before the break, with the Aussies leading 17-7 at halftime. The second half proved a good fightback by South Africa. Geduld scored a second and when Gans scored and Selvyn Davids converted, the South Africans were in the lead, 21-17. Australia scored twice though to clinch the match and a place in the last eight.
The quarterfinals, to be shown live on SuperSport, are (SA times):
03h16: Fiji v Australia
03h38: New Zealand v France
04h00: South Africa v England
04h22: USA v Spain