PRIDDIS, Alberta - Three-time champion Lydia Ko was back on the Canadian Pacific Women's Open leaderboard. Canadian star Brooke Henderson got left behind after a late start.
The top-ranked Ko shot a 5-under 67 on Thursday at Priddis Greens in the round delayed for nearly three hours because of lightning, leaving her two strokes behind leader Chella Choi.
''I had lunch like three times and I had fro-yos,'' Ko said. ''I wish there could be a switch where we could put out the sun or put some overcast. But when it comes to weather, we can't control it, so when it's that case, you just have to go with it.''
The 18-year-old Henderson was 1 under with three holes left when play was suspended because of darkness. Henderson, from Smiths Falls, Ontario, beat Ko in a playoff in June in the KPMG Women's PGA Championship for her first major title, and successfully defended her Cambia Portland Classic title in early July.
Choi was 7 under with four holes left. Celebrating her 26th birthday, the South Korean player made consecutive birdies on the par-5 18th and first holes and also birdied the par-4 second and fourth.
Northern Ireland's Stephanie Meadow was a stroke back after a 66. France's Karine Icher - playing alongside Choi - was 6 under with four holes left.
Ko has won the event three of the last four years, the first two as an amateur. The New Zealander won in 2012 at Vancouver Golf Club at 15 years, 4 months to become the LPGA's youngest winner and fifth amateur champion. She successfully defended her title in 2013, winning by five strokes in Edmonton. Last year back at Vancouver as a pro, she beat Stacy Lewis in a playoff.
The 19-year-old has four LPGA victories this season, winning the ANA Inspiration in April for her second major title. She was second last week in the Rio Olympics, five strokes behind Inbee Park. On Thursday, Ko had six birdies and one bogey.
''I played really solid, birdied the first hole straight off the bat,'' Ko said. ''I was putting really well and hit the ball pretty good throughout the round.''
Meadow, the 24-year-old former Alabama player, birdied the final two holes, closing with a right-to-left breaking 20-footer on the par-4 ninth.
''It was gray and it looked like it was rain and windy, so that's pretty much Ireland in a nutshell,'' Meadow said. ''But definitely I think it's nice to know that I can play in those conditions. I've done it a lot, even though it's when I was little. But I've still done it and scored, so I know I can do it.''
South Korea's Mirim Lee and Mi Jung Hur matched Ko at 67, and second-ranked Ariya Jutanugarn of Thailand also was 5 under with four holes to play. Jutanugarn won the Women's British Open for her fourth victory of the year, then withdrew during the Olympics because of a left knee injury.
Past champions Suzann Pettersen and So Yeon Ryu shot 68. Pettersen won in 2009 at Priddis Greens, and Ryu two years ago at London Hunt in Ontario.
''I have a really good confidence vibe here,'' Ryu said.
Lewis was 4 under with four holes left. Coming off a tie for fourth in Rio, the 11-time tour champion is winless in 57 starts since June 2014. The Texan has 11 runner-up finishes during the drought.
Michelle Wie, the 2010 winner in Winnipeg, Manitoba, had a 71.
Juli Inkster holed out from the fairway for eagle on the ninth. The 56-year-old Hall of Famer finished off a 70 just before dark.
Lorie Kane matched Hollis Stacy's tournament record with her 26th straight appearance in the event, Inducted into the Canadian Golf Hall of Fame on Tuesday night, the 51-year-old Kane shot 73.
Karrie Webb also had a 73. She won the 1999 du Maurier Classic at Priddis Greens, the then-major championship that folded because of Canada's restrictions on tobacco promotions.
The tour will remain in Canada next week for the Manulife LPGA Classic in Cambridge, Ontario.