An impressive round-robin record doesn't necessarily mean Canada's Jennifer Jones is a lock to win a world championship for the first time in a decade.

The Winnipeg team will need to clean up a few areas for a clear path to the podium.

Jones (12-0) has had inconsistent draw weight throughout the competition at the North Bay Memorial Gardens. It was a factor again Friday morning in an 8-5 win over Japan's Tori Koana.

Jennifer Jones' rink beat Japan 8-5 to remain undefeated at the 2018 World Women's Curling Championships, and earn a spot in the tournament's semifinal. 0:39

Jones shot 79 per cent — the lowest percentage on her team — and it kept Japan in the game. She was just 73 per cent on her draws.

Canada's overall performance was solid but far from spectacular. It has been a consistent theme through the week.

"We're making big shots when we have to," Jones said. "That's really what winning is all about."

Jones has stepped up when needed and is the No. 1 seed in the six-team playoff. She will have choice of hammer or stone selection in semifinal play Saturday night.

Canada kept its unbeaten streak alive Friday night with an 8-5 win over American Jamie Sinclair in the round-robin finale.

Jennifer Jones led team Canada to a perfect 12-0 record in the round robin stage of the World Women's Curling Championship with two 8-5 wins against Japan and the USA. 2:12

Sweden's Anna Hasselborg (10-2) owns the other semifinal berth. South Korea's EunJung Kim (8-3), Russia's Victoria Moiseeva (7-5), the U.S., (6-6) and Anna Kubeskova of the Czech Republic (6-6) locked up the other playoff spots.

China's Yilun Jiang (6-6) also finished with a .500 record but did not advance due to losses in head-to-head matchups.

On Saturday morning, No. 3 South Korea will play the sixth-seeded Americans while No. 4 Russia meets the fifth-seeded Czechs. Canada will play the lower-seeded victor in one semifinal while Sweden will play the other winner in the afternoon.

Jones started strong last weekend by knocking off some tournament lightweights with relative ease. She later withstood challenges from South Korea, Sweden and Russia — in successive draws — despite some nervous moments.

Second Jill Officer skipped Friday morning's game to rest after coming out early the day before. She was replaced by alternate Shannon Birchard before returning for the night game.

The Jones effect

Canada has done well putting pressure on its opponents. The host side, which includes lead Dawn McEwen and third Kaitlyn Lawes, entered the last draw with a competition-best force efficiency of 70 per cent.

One big factor that you won't find on the stat sheet is what could be called the Jones effect. It may be in play over the final weekend.

The 2014 Olympic champion is an imposing presence on the ice, anchoring the top-ranked women's team in the world. It can make opposing skips crumble in the later ends when the game is on the line.

A boisterous home crowd will make things even tougher for Canada's opposition on Saturday night.

It likely won't be an issue for second-seeded Hasselborg, who beat host South Korea in the pressure cooker of the Olympic final in Pyeongchang.

'Good enough' in win over Japan

On Friday morning, Jones scored three points in the third end and took an 8-2 lead by stealing a pair in the sixth. Japan picked up three straight singles before Jones ran Koana out of stones in the ninth end.

"We're happy with it," said national team coach Elaine Dagg-Jackson. "It wasn't the best game we played all week, but it was certainly good enough."

Birchard played third for Jones at the Scotties Tournament of Hearts while Lawes was preparing for the Games. Birchard has looked just as strong playing the second position here and threw 88 per cent against Japan.

The U.S.-Canada game turned in the eighth end when Jones delivered a hit for three. A sellout crowd of 3,887 was on hand to push the overall attendance to 51,771.

Dagg-Jackson said Officer has battled some blister issues but would play through them. Officer recently announced she would be stepping away from competitive curling after this season.

She plans to serve as an alternate for Jones at select events next season.

New playoff format

With the addition of a 13th team in the world championship field this year, the traditional four-team Page Playoff system was scrapped in favour of the six-team setup.

Joining China on the sidelines were Japan (5-7), Switzerland (5-7), Scotland (5-7), Denmark (3-9), Germany (3-9) and Italy (2-10).

Semifinal winners will play for gold Sunday and semifinal losers meet for bronze.

Ottawa's Rachel Homan ran the table en route to winning gold at last year's world championship in Beijing.

Jones is making her sixth career world women's curling championship appearance. Her lone victory came in 2008 in Vernon, B.C.