Taiwanese golfer Yani Tseng has vaulted to second in the women's world golf rankings after winning the Kraft Nabisco Championship, the first major tournament of the season, leaving her in good position to make a run at dethroning long-time world No. 1 Lorena Ochoa. Tseng, who started last week ranked sixth, regained the spot she had occupied between Nov. 24, 2008 and Aug. 31, 2009 after her one-shot victory in the Kraft Nabisco. She has not been ranked outside the top six since winning her first major, the LPGA Championship, in June 2008. The rankings are determined by a complicated formula weighting players' performances over the past 104 weeks on all major women's professional golf tours around the world. Points earned based on tournament finishes are divided by tournaments played to give a points average used to rank the players. Anything over a 10 is considered phenomenal. Ochoa who has reigned as the top player in woman 's golf for 155 weeks, averaged over 13 for much of 2009, far outdistancing Tseng and other challengers. Tseng had fallen as far as sixth in the rankings after suffering through an inconsistent second half of 2009, but her recent surge (she also won the Australian Women's Open in mid-March) and Ochoa's inability to reproduce her incredible run between 2006-2008 have pulled the two much closer. Ochoa, who won only three events in 2009 after averaging seven tour wins per year the previous three years and who has not won a major in two years, has grown vulnerable at the top, falling to an average of 9.34, only 0.53 ahead of Tseng' s 8.81. Another LPGA tournament win by Tseng could end Ochoa's reign, but Tseng herself has to be careful about maintaining her own standing as another three top players -- Korea's Jiyai Shin, Norway's Suzann Pettersen, and Japan's Ai Miyazato -- are fairly closely bunched behind the 21-year-old Taiwanese. Aside from soaring up the world rankings, Tseng catapulted to the top of other major lists by winning this past weekend's major in Rancho Mirage, California. Her US$300,000 first prize made her the leading prize money winner on the LPGA Tour after its first four events of the year. She also moved into the top spot in the standings for the highly coveted LPGA Player of the Year award, ahead of Miyazato and Pettersen. 