New Zealand beat Japan 6-5 by scoring singles on six ends at the Dunedin Ice Stadium.
"Our game plan was to keep the stones in front of the house and keep it blocked up," skip Wendy Becker said.
When the New Zealand concentration lapsed, Japan scored a two on the third end and three on the fifth to lead 5-3.
New Zealand drew level on the next two ends and the game was won on the last end.
Second Pauline Farra put the winning stone into the house and Japan was not able to break past the guards.
It was New Zealand's second win in four games.
Its other win was against the United States, 8-4.
The experienced Scottish team started badly when it lost its first two games.
But it has come back strongly with wins against the United States, 9-2, and Italy, 8-5.
The fourth end was key.
Skip Marion Craig (51), a Scottish beef farmer, took out the scoring stone to give her team three shots and the lead 7-2.
Sweden beat Switzerland 8-6 in a game that was crucial to the two teams vying for a podium spot.
Switzerland looked to have the game in its grasp when it scored a three on the sixth of the eight ends to lead 6-4.
But Sweden, skipped by the experienced Ingrid Meldahl (57), came back to level pegging with a two on the penultimate end.
Meldahl, a surgeon, put in a block with the first two stones and second Anta Hedstrom made a steal by putting a scoring shot into the house.
The Swiss became desperate and third Lotti Pieper let fly with an aggressive stone that caused havoc in the house.
But the end result was a second shot to Sweden.
Canada, the defending gold medallist, started aggressively by scoring a two and four on the first two ends to lead 6-0 against the United States.
It won 7-5.
On the fourth end, the United States had four rocks in the house.
Third Cheryl Noble played a spectacular shot to take out three US stones to limit the scoring to one.
The US had crept up to be just two shots down, 5-7, before the final end.
But the eighth end finished in a stalemate with no shots added, when all the stones were pushed out of the house.
Defending champion Canada retained its unbeaten record when it trounced England 10-2 in the blue section of the men's competition.
Japan and Scotland moved into semifinals contention with wins yesterday.
Japan beat Hungary 8-3 and Scotland held out a strong challenge when it beat Australia 6-4.
The United States beat Switzerland 6-5 to retain its unbeaten record in the red group.
Sweden and Switzerland have two wins and are contenders for the other semifinals spot.
