Yoo had a five-shot lead until giving up three shots on the last two holes with a pair of three-putts, one of them a double bogey on the par-3 eighth when her tee shot went long and down a steep slope.
Stacy Lewis, the LPGA player of the year, needs to win the Titleholders to have any chance of winning the money title. She was within two shots of the lead after an eagle on the par-5 13th, but the 27-year-old American dropped two shots coming in and had to settle for a 70.
Pettersen went 20 tournaments to start the year without a win until she broke through with back-to-back victories in Asia. Last week, she tied for 12th in Mexico.
She played in the same group with Cristie Kerr, whose win last week in Mexico was her first in two years. Kerr opened with a 67 at TwinEagles and was a shot behind, along with U.S. Women's Open champion Na Yeon Choi.
The warm weather and only a gentle breeze allowed for good scores, with 48 players at par or better among the 73 in the field. There were a few exceptions, starting with Michelle Wie. She was wild with her first tee shot, and it finally caught up to her on the back nine. Wie had an 81.
HONG KONG OPEN
HONG KONG (AP)—Spain's Javier Colomo shot a 6-under 64 to take the first-round lead in the Hong Kong Open, leaving top-ranked defending champion Rory McIlroy nine strokes back.
McIlroy admitted to feeling lethargic after shooting a 73.
Spain's Miguel Angel Jimenez, the 2008 winner, was a stroke back at 65 along with Australia's Andrew Dodt in the event sanctioned by the European and Asian tours.
MELBOURNE, Australia (AP)—Australia's Matthew Guyatt upstaged the marquee players at the Australian Masters, shooting a 7-under 65 to take a two-shot lead after the first round at Kingston Heath.
Adam Scott had five birdies on his final nine holes to join defending champion Ian Poulter of England and New Zealand's Michael Hendry at 67. Northern Ireland's Graeme McDowell opened with a 71.
SOUTH AFRICAN OPEN
JOHANNESBURG (AP)—South Africa's Merrick Bremner birdied six of his first nine holes and finished with an 8-under 64 to tie the course record in the first round of the South African Open.
Sweden's Henrik Stenson and South Africa's Matthew Carvell were two strokes back at Serengeti Golf and Wildlife Estate. South African star Charl Schwartzel recovered from a double-bogey 5 at the 12th for a 68, Germany's Martin Kaymer had a 70, and South Africa's Branden Grace shot 72.
The tournament is sanctioned by the Sunshine and European tours.