PRINCE GEORGE, B.C. — Canada's Kerri Einarson will have to wait to clinch a playoff berth in the women's world curling championship after an 8-7 loss to South Korea on Thursday night in a match that needed an extra end.

With the loss, Canada now sits at 7-3 for the tournament in a tie for third with South Korea.

Canada's 9-3 win over the United States on Thursday morning brought the host country to a 7-2 record prior to the game against South Korea.

"I think we're in a good space right now, headspace, and feeling very confident going into the rest of the week," Einarson said.

The top six teams at the conclusion of the round robin Friday continue playing into the weekend for a chance at a world title Sunday at the CN Centre.

With a fifth straight win — their fourth was a forfeit by Scotland — Einarson's foursome out of the Gimli Curling Club controlled their playoff destiny.

Switzerland was assured of finishing first in the standings, however, with a 10-0 record Thursday.

Back-to-back defending champion Silvana Tirinzoni earned one of two byes to Saturday's semifinals that go to the top two seeds.

Third through sixth plays off earlier Saturday to get to the evening semifinals.

Sweden ranked second at 8-2, but Canada at No. 3 remained in the hunt for the other semifinal bye.

Einarson's round-robin win over the Swedes would rank Canada higher in the event of a tied record.

Japan was 6-4 ahead of Denmark and the United States even at 5-4. Germany and Norway were both 5-5 followed by Italy at 3-7, the Czech Republic at 2-7 and Turkey winless in nine games.

Canada caps the preliminary round Friday against the Germans and the Czechs.

The Scots withdrew Sunday because four players tested positive for COVID-19.

Since the seventh end of Monday's win over the Danes, Einarson, third Val Sweeting, second Shannon Birchard and lead Briane Meilleur have settled into their ice reads and execution.

Sweeting posted a fourth straight game of over 90 per cent shooting accuracy Thursday. Birchard shot 100 per cent through seven ends against the Americans, who conceded after the eighth.

Their hoarse skip — Einarson's voice routinely takes a beating over the course of an event — was plus-90 on her takeouts against the U.S.

"It's my winter voice," Einarson said. "Every single event I curl in, it's gone."

Einarson and company opened last year's world championship 1-5 in Calgary's curling bubble.

Fuelled by fatalism, they won six of seven to squeak into the sixth and last playoff spot before losing out.

After a 2-2 start on opening weekend, their road in Prince George has been less of a white-knuckle ride.

"It's night and day compared to last year," Birchard said. "I think we're really enjoying ourselves, whereas last year, we were backs against the wall at this point, and it was very stressful.

"We're super comfortable and I think that's really played into how we've been out there on the ice. I think we play best when we're relaxed, and we're having fun and enjoying ourselves."

Einarson had draw weight locked in early Thursday and U.S. skip Cory Christensen did not, which led to Canada stealing four points over the first three ends.

"Gets tricky when you don't have your draw eight and you have to try and make super-precise freezes," Christensen said.

Another missed draw by the American skip in the fifth end left Einarson a makeable peel to score three for a 7-1 cushion in front of 1,446 at the CN Centre.

Christensen swapped out second Vicky Persinger, who played Olympic mixed doubles last month in Beijing, for alternate Sydney Mullaney to start the sixth end.

"We just figured it wasn't our best game and we were likely not going to pull it off so we wanted to get our alternate in there," Christensen said.

While Canadian championships feature tiebreaker games when teams are tied for the last playoff spot, the world championships do not.

If two countries are tied Friday, the winner of their round-robin matchup ranks higher. If three or more teams are tied, their record of the games between them provides seedings.

If that doesn't resolve the deadlock, the average distance of all pre-game draws which determine which team gets hammer are used for ranking.

This report by The Canadian Press was first published March 24, 2022.