And she knows it might take more than one season to get there.
Pettersen and Tseng tee off in the Women's Australian Open with a strong field at Royal Melbourne Golf Club including world No. 4 Christie Kerr, No. 7 Jiyai Shin, No. 9 Stacy Lewis, No. 10 Brittany Lincicome and Australia's former world No. 1 and four-time champion Karrie Webb.
"It's always been a dream of mine," she said. "And I definitely think my game is there.
"Yani's got a great head start over all of us and it's probably going to take more than a season to catch up with her."
Tseng has shown off her new, more powerful swing at Royal Melbourne, honing the tweaks to her technique as she familiarized herself with the sandbelt course.
Tseng started 2011 with a title at the Women's Australian Open and went on to win a total of 12 tournaments, including two majors and seven on the LPGA Tour to finish a long way clear atop the rankings.
The 23-year-old Taiwanese started preparing for the 2012 Australian tournament — which kicks off a three-week Asian swing before the LPGA Tour moves to U.S. soil next month in Arizona — by watching the Presidents Cup at Royal Melbourne's Composite course last November.
Pettersen said she tried to ignore Tseng's approach, preferring to concentrate on her own game.
"I look at my game and what I can do better to get the most out of it every day," she said. "She's a great No. 1, she's very aggressive, very fearless and obviously has a lot of confidence at the moment. But I've beaten her before so I know you can do it."
Pettersen is now looking for consistency, transferring her good form on the tour to major titles.
"I look back at 2011 as a pretty good year," she said. "I had three wins, there was a lot of consistent golf but I wasn't really in contention for the majors, which was a bit painful.
"That's one thing I would like to do, try to prepare better in the weeks before the majors so I can go in less stressed about how the game is feeling."
Pettersen also paid close attention to the Presidents Cup in preparation for this week's tournament, noting the number of balls that sped across the glassy greens.
"I may play a bit more conservatively. You have to take what the course gives you each day. I know it can swap around very easily and change drastically from morning to afternoon," she said.
Also in the field this week are new Australian Ladies Masters champion Christel Boeljon of The Netherlands and 14-year-old New Zealand amateur Lydia Ko, who recently became the youngest winner of a pro event with victory in the New South Wales Open.