Caroline Hedwall fired a 6-under 64 on Saturday to race into a 1-stroke lead at the Canadian Women's Open.
Hedwall, who is seeking her first career win on the LPGA Tour, finished 54 holes at Royal Mayfair Golf Club at 10-under-par 200.
"I was a little tired on Monday, Tuesday and also Wednesday, but when the tournament starts I think last week just gave me a lot of energy and self- confidence, so I can't feel anything," said Hedwall, who became the first player in Solheim Cup history to go 5-0 last week.
Suzann Pettersen carded a 5-under 65 to join defending champion Lydia Ko (67) in second place at 9-under, while I.K. Kim (65) and Brittany Lincicome (66) shared fourth at 8-under 202.
Paula Creamer (69), Gerina Piller (67) and Karine Icher (70) are tied for sixth at minus-7.
Second-round co-leaders Inbee Park and Karine Icher both struggled on Saturday, tripping to a 74 and 75, respectively, to fall well off the pace.
Ko took advantage of the co-leaders struggles to race into the lead at 10- under with an outward 31 that included birdies at the first, sixth, seventh and ninth.
But the 16-year-old bogeyed the 12th to fall back to 9-under and into a tie for the lead with Pettersen, who recorded gains at Nos. 2, 5, 7, 8, 12 and 14 around a bogey at the 13th to meet her there.
Hedwall, meanwhile, birdied four of her first six holes to move to 8-under and after dropping a shot with a bogey at the eighth, poured in birdies at the 12th and 14th to join Ko and Pettersen atop the leaderboard at 9-under.
Ko then dropped off the pace with another bogey at the 13th before Hedwall made it two birdies in a row at the 15th to grab the outright lead.
The Swede parred her final three holes to remain there.
"I'm just looking forward to tomorrow," Hedwall said. "It will be exciting playing in the last group hopefully. I won on the European Tour, now I'm just waiting for my first LPGA victory."
Ko would birdie the 14th and par her final four holes to finish at 9-under, while Pettersen also followed her birdie at the 14th with four straight pars to head into the final round a shot off the pace.
"I played pretty well out there," said Ko. "I made five birdies and two bogeys. I was overall really happy, and I was 8-under coming into the final round last year, so one shot better, which leaves me in a good place."
NOTES: Hedwall's 64 tied the course record ... It is the first time in her career that Hedwall has held the third-round lead ... Hedwall does have eight career victories between the Ladies European Tour and the Australian Ladies Professional Golf Tour ... Eun Hee Ji recorded a hole-in-one at the fourth hole.