Reigning Olympic champion Jennifer Jones of Manitoba took advantage of the hammer in the extra end for an 8-7 victory over two-time defending Scotties champion Rachel Homan on Monday night at Mosaic Place.
Jones joined Alberta's Val Sweeting in first place at 5-0 while Homan fell to 4-1 after eight draws of play.
In the extra end, Homan had a stone at the edge of the four-foot and a guard up top. Jones came through with a draw to the button that was a no-doubt winner as it approached the rings.
"It gets the heart racing and the blood going, but that's what sport is all about," Jones said. "That's honestly what I love about the sport is that you can win or lose on any given day.
"It's what we train for, it's what we play for, it's what makes it exciting for the fans."
Jones also ended Homan's 22-game winning streak at this event. Homan's last loss at the Scotties was to Jones at the 2013 tournament in Kingston, Ont.
Homan went on to beat Jones in the final that year and ran the table last year in Montreal.
"It's a new tournament," Homan said of the streak. "I don't really count all those other (wins from) random tournaments before this. Every game is going to be tough and we're playing well so we've just got to keep playing like that."
Jones didn't play at the Scotties last year. She instead represented Canada at the Sochi Games and won the gold medal.
"Obviously they're doing well, so you want to try to knock some people back," Jones said. "It was a big win for us tonight but we've got (a lot) of games left.
"It's just one more win and we've got a lot more winning to do."
Sweeting, meanwhile, held off Prince Edward Island's Suzanne Birt 6-5. Earlier in the day, the Alberta skip rolled to a 7-2 victory over Heather Strong of Newfoundland and Labrador.
Homan cruised to an 8-3 win over B.C.'s Patti Knezevic in her other game while Jones dumped Strong 9-3.
Canada coach Richard Hart likes what he's seen from the defending Scotties champions in the early going.
"I think even as steady as they've been, I think they've got another gear," Hart said. "And that's what they're aiming towards later on in the week."
Saskatchewan's Stefanie Lawton won both of her games to move into a fourth-place tie with Northern Ontario's Tracy Horgan at 3-2.
Lawton topped Quebec's Lauren Mann 8-3 before shading Ontario's Julie Hastings 4-3.
Horgan beat Nova Scotia's Mary-Anne Arsenault 8-4 and then topped New Brunswick's Sylvie Robichaud by the same score in the evening. Earlier in the day, B.C. downed P.E.I. 7-4, Nova Scotia edged New Brunswick 5-4 and Ontario edged Quebec 6-5.
There was a four-way tie for sixth place as Ontario, Nova Scotia, Newfoundland and Labrador and P.E.I. were even at 2-3. Quebec and B.C. were next at 1-4 while New Brunswick remained winless at 0-5.
The top four teams at the end of round-robin play Friday morning will make the playoffs. Medal games are scheduled for Sunday.
Follow @GregoryStrongCP on Twitter.