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 dropped two shots coming in and had to settle for 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.
HONG KONG OPEN: In Hong Kong, Javier Colomo shot 6-under-par 64 to take the first-round lead, leaving top-ranked defending champion Rory McIlroy nine strokes back.
McIlroy admitted to feeling lethargic after shooting 73.
Miguel Angel Jimenez, the 2008 winner, is a stroke back at 65 along with Andrew Dodt in the event sanctioned by the European and Asian tours.
AUSTRALIAN MASTERS: In Melbourne, Australia, Matthew Guyatt upstaged the marquee players, shooting 7-under-par 65 to take a two-shot lead after the first round at Kingston Heath.
Adam Scott joined defending champion Ian Poulter and Michael Hendry at 67.
SOUTH AFRICAN OPEN: In Johannesburg, Merrick Bremner birdied six of his first nine holes and finished with 8-under-par 64 to tie the course record in the first round. Henrik Stenson and Matthew Carvell are two strokes back.
DUNLOP PHOENIX: In Miyazaki, Japan, Luke Donald shot 6-under-par 65 to take a share of the lead after the first round of the Japan Tour event.
Donald is tied with Brendan Jones and Hideto Tanihara. Koichiro Kawano and Shunsuke Sonada are two strokes behind the leaders.