Norway's Suzann Pettersen birdied the final hole on Thursday and joined South Koreans So Yeon Ryu and Sun Young Yoo atop the leaderboard at the LPGA's season-ending Titleholders.
Pettersen, winner of back-to-back LPGA titles in Asia last month, had six birdies and no bogeys in her six-under 66 at TwinEagles.
Yoo got as low as nine-under, but closed her round with a double-bogey and a bogey to fall into a tie for the lead in the $1.5-million tournament.
"I hit the ball great all day, but I'm a little disappointed how I finished the last couple of holes," Yoo said of the two three-putts that ended her round.
"But still, six-under was a good score," added Yoo, who won the Kraft Nabisco Championship this year when I.K. Kim missed a one-foot putt for the victory then lost to Yoo in the playoff.
"I still have 54 holes to play, so I feel good," Yoo said.
Ryu, who has already locked up Rookie of the Year honors, had seven birdies and just one bogey for her share of the lead.
The top trio were one stroke in front of a quartet of players on 67: South Korea's Na Yeon Choi, Australian Lindsey Wright, France's Karine Icher and American Cristie Kerr - the winner on Sunday of the Lorena Ochoa Invitational in Mexico.
South Korea's Jiyai Shin was among another four players tied on 68 on the tightly bunched leaderboard.
Player of the Year Stacy Lewis, who needs a victory to have a shot at capturing the LPGA money title, settled for a 70.
Pettersen has come alive late in the season, winning the LPGA HanaBank Championship in a playoff in South Korea then following up with a victory in Taiwan.
"I feel like my shoulders are fairly freed up after winning two in Asia," Pettersen said. "I don't feel like I really have to go out and do anything. That makes the game that much easier.
"My big goal now is to prepare and be well for 2013 and hopefully come out strong the way I finish, and hopefully get another three rounds together and see where that takes me for this tournament."
Pettersen was paired with Kerr, whose victory last week was her first in two years.
"I played awesome last week and carried that into this week," Kerr said.
Optimum scoring conditions saw 48 players in the field of 73 at par or better.
Not everyone could take advanage, however. Michelle Wie posted an 81, while world number one Yani Tseng opened with a 75.