New Zealand fought off a spirited Portuguese outfit 19-12 in the afternoon before returning in the evening and struggling to see off France 19-7. England was pushed by Japan before winning 33-14 and then overcame the United States 37-12.
The quarterfinal draw for Sunday is: New Zealand plays Portugal, South Africa faces Fiji, Samoa meets Australia while England takes on Russia.
New Zealand coach Gordon Tietjens said his team - joint leaders with the English in the Sevens World Series coming in to the tournament with points worth double - had to learn from its mistakes to have any hope of lifting the title.
"We've won our pool and the thing that is going to get our experienced players up is the younger players putting pressure on them," he said. "You learn from close games.
That's just what happens at this event - the unfancied teams lift against the top sides and that's what we've been seeing today.
"We'll have to go away now and have a think and regroup.
If you're not up for it mentally you're going to get beaten. I've seen it happen." The Kiwis were conspicuously lacking spark in their last game, and their coach said his players were aware of the importance of giving the people back home a lift following the Christchurch earthquake tragedy that claimed 182 lives on Feb. 22.
"If we can put everything that's been happening behind us and click as team, we'll certainly be doing everything we do for the people back home," Tietjens said.
The English left Hong Kong Stadium confident they could raise their games when it counts again on Sunday's final day.
"The Sunday here is massive, it is just the biggest atmosphere," said Oliver Lindsay-Hague, who scored two tries against Japan and another against the Americans with a brilliant goose-stepping solo effort.
"We're joint top points with New Zealand in the world series, so we have to get the 30 points here and get clear of them. It's really important for us to win the world series this year, that's the goal we set ourselves. We've got a lot more in us." Other teams that remain unbeaten after day two to top their groups were reining champion Samoa, South Africa, Fiji and Australia.
But it was the South Africans who impressed the most, shrugging off Hong Kong 45-0 and then Wales 42-12. And they had Sevens World Series leading points and try scorer Cecil Afrika to thank as he scored three tries and 11.
"With Cecil it is all about the athletic ability," South Africa coach Paul Treu said. "He is a constant threat to the defense line. But more importantly is the guys around him who must do the hard work so Cecil can dance. Every player must commit to their jobs out on the field so he can play to his potential." There was some cheer for Japan after its first win of the event, 17-12 over China. It had been hard graft before then for the Japanese, who had their arrival in Hong Kong delayed due to the devastation of the March 11 earthquake and tsunami, responsible for more than 10,000 deaths.
