NORTH BAY, Ont. -- Canada's Jennifer Jones locked up the top seed at the world women's curling championship Friday with an 8-5 win over Japan's Tori Koana.

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.

The Winnipeg skip, who improved to 11-0, will close out round-robin play Friday night against American Jamie Sinclair.

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

Canadian alternate Shannon Birchard replaced second Jill Officer in the lineup. Birchard played third for Jones at the Scotties Tournament of Hearts while vice-skip Kaitlyn Lawes was preparing for the Winter Olympics.

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

As top seed, Jones will have choice of hammer or stones in the playoffs. The top two seeds earn semifinal berths and the four remaining teams will play qualification games Saturday morning.

Sweden's Anna Hasselborg (10-1) and South Korea's EunJung Kim (7-3) locked up playoff berths Thursday.

Hasselborg, the reigning Olympic champion, has secured the No. 2 seed. The other seeding positions will be finalized later Friday.

Sinclair, a dual citizen who grew up in Manotick, Ont., dropped an 8-6 decision to the Czech Republic's Anna Kubeskova on Friday morning.

That left Russia's Victoria Moiseeva in sole possession of fourth place at 6-4. The United States fell into a fifth-place tie with the Czechs at 6-5.

In other early games, Germany's Daniela Jentsch outscored Switzerland's Binia Feltscher 10-6 and China's Yilun Jiang held off Denmark's Angelina Jensen 10-9.

China was in seventh place at 5-6. Japan and Switzerland were out of the playoff mix at 4-7.

The standings were rounded out by Scotland (3-7), Denmark (3-8), Germany (3-8) and Italy (2-9).

Qualification winners advance to the semifinals, with the winners moving on to play for gold Sunday. Semifinal losers will play for bronze.

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

Jones, who won Olympic gold in 2014, is looking for her first world title since 2008. It was her lone gold medal in five previous world championship appearances.