SINGAPORE, Feb 28, 2013 (AFP) - Tseng's 25-foot downhill putt across the 18th green, a contender for shot of the day, drew broad smiles and an arms-aloft celebration from the Taiwanese ace as she rocketed up the standings to lie three shots behind Munoz with a 68.
Munoz ended a hot first day at the par-72 Sentosa Golf Club two shots clear on seven-under-par 65 after dropping four birdies on her front nine and another three on the way back.
The Spaniard also pulled out a big par save on 16 and lipped out a birdie attempt on 17, as she finished bogey-free and ahead of five players tied for second, including American world number four Stacy Lewis.
Tseng, another shot back and hunting her first win in nearly a year, was among four players on 68 including America's Paula Creamer, who made light of whiplash sustained in a car crash after last week's event in Thailand.
Japan's Ai Miyazato was forced to pull out of the Singapore event as she recovers from similar injuries from the five-car smash in Bangkok, which also involved Norway's Suzann Pettersen.
Tseng, the "Pride of Taiwan", carded three birdies and a bogey over her first seven holes, and then parred 10 in a row in what looked destined to be a quiet round -- until her grandstand finish.
Afterwards, she revealed that the unerring final stroke won her a bet with her manager, who will now have to accompany her on a skydiving trip.
"I told her I need some motivation, a little energy. So I told her a 69 is a tie and 68 I win. Her bet was for a Louis Vuitton bag and if I win, she will go skydiving with me in Hawaii," said Tseng.
"When that putt dropped, I was so happy. I was looking for her, I saw her face, I thought she was going to cry, so I think that's very good motivation.
"If you have a bet with your friend, it feels so good. Today that really kept me very patient and relaxed all day."
Munoz, 25, recorded her first LPGA Tour win last season and her 65 went down as one of the best opening rounds of her career. She said she was helped by starting in the morning's first group, with the run of the course and pristine greens.
"I don't know what it is, but my best three rounds on tour have been first tee time," she said. "I really like it, you don't have to wait, it's super-nice, the greens are perfect. I think it gets me going."
World number two Choi Na-Yeon, who is threatening to supplant Tseng at the top of the rankings, shot 69 to lie alongside Thailand's Ariya Jutanugarn, 17, who recovered well from the final-hole disaster which cost her victory in Pattaya last week.
Former teen prodigy Michelle Wie, now 23 and ranked 73rd, finished the day one under par, but Angela Stanford's chances of a successful title defence looked remote after she signed for a wayward 76.
Leading scores on Thursday after round one of the HSBC Women's Champions at Singapore's Sentosa Golf Club (par 72):
65 - Azahara Munoz (ESP)
67 - Lizette Salas (USA), Karin Sjodin (SWE), Stacy Lewis (USA), Pornanong Phatlum (THA) Yoo Sun-Young (KOR)
68 - Chella Choi (KOR), Paula Creamer (USA), Danielle Kang (USA), Tseng Yani (TPE)
69 - Brittany Lincicome (USA), Amy Yang (KOR), Chie Arimura (JPN), Nicole Castrale (USA) Jodi Ewart Shadoff (ENG), Choi Na-Yeon (KOR), Ariya Jutanugarn (THA), Candie Kung (TPE), Feng Shanshan (CHN)
70 - Katie Futcher (USA), Catriona Matthew (SCO), Caroline Hedwall (SWE), Cindy Lacrosse (USA), Morgan Pressel (USA), Kang Hae-Ji (KOR), I.K. Kim (KOR), Lee Il-Hee (KOR), Karine Icher (FRA)