Angela Stanford and Catriona Matthew fired matching 8-under 63s on Thursday to share the lead after the opening round of the Manulife Financial LPGA Classic.
Inbee Park, who has six wins this season including all three majors and the last three events overall, is among a group of five players tied for third at 6-under 65.
"I think it was an excellent round," stated Park. "I had a really good start this morning, 5-under through seven holes. I missed a couple opportunities on the back nine, but I'm pleased with the way I played today."
Park is joined by Hee Young Park, Meena Lee, Belen Mozo and Irene Cho.
Ryann O'Toole, Chella Choi, Jenny Shin, Amy Yang and Ji Young Oh are tied for eighth at 5-under.
Defending champion Brittany Lang carded a 2-under 69 during her first round at Grey Silo Golf Course to sit in a large group tied for 41st.
Matthew started on the 11th tee and opened with a par before tripping to a bogey at the 12th.
She would not drop a shot for the remainder of the day, however, and bounced back with birdies at the 14th, 16th and 18th to move to 2-under.
After rolling in another birdie at the second, Matthew reeled off three straight gains from the fifth to race to 6-under.
She then ended her sizzling closing stretch with a pair of gains at the ninth and 10th, capping her round with a 25-foot putt, to head into the clubhouse with the lead.
"I hit it close all day, which gives you a lot of chances, and then obviously I putted well," said Matthew. "I gave myself a lot of chances, but took advantage of them."
Stanford went out with the afternoon wave and also started on the 11th hole.
She parred her first three holes before closing out the back side with a trio of birdies at the 14th, 16th and 18th.
Stanford then rolled in gains at the third and sixth to move to 5-under, and after parring the seventh, she closed with three straight birdies from the eighth to meet Matthew atop the leaderboard.
"I kind of thought about it on the eighth tee box that I had three holes left and I knew one of them is a par-3 and the other two par-4s, I might have a wedge in. So I really just tried to hit quality shots into the greens and had the opportunities I wanted and made them," Stanford said about her closing stretch.
Cho was the lone member of the group tied in third to record a bogey-free round, while Hee Young Park, Inbee Park, Lee and Mozo all countered a single bogey with seven birdies.
NOTES: Matthew set a new career low with her 63. She had shot 64 on four separate occasions ... Inbee Park has now shot under par in the first round in 10 of 13 events played this season, not including the Pure Silk-Bahamas LPGA Classic ... Matthew has four top-10 finishes in 12 starts this season, but has not recorded a win since the 2011 Lorena Ochoa Invitational.