And with one round left in the LPGA season, there's plenty left to decide.
Kerr shot a 4-under 67 - her third straight round in the 60s this week - Saturday to match Jang at 13 under at Tiburon Golf Club. Jang closed with a bogey for a 69, a round where she twice had to deal with nosebleeds she thought were brought on by hot, humid conditions.
''I feel fresh and kind of ready to perform,'' Kerr said. ''I don't feel like this is the last tournament of the year for me. It feels like there's a couple left. Hopefully that can carry me through tomorrow.''
The top-ranked Ko and Gerina Piller were tied for third at 11 under, and 14 players are within six shots of the lead going into the final round. Ko had a 69, and Piller shot 67.
But what matters more to the 18-year-old Ko is all the tournaments within this tournament - she goes into Sunday in position to hang on to the world's No. 1 ranking, plus walk away with the Player of the Year award, the scoring title, the money title and, for the second straight year, the $1 million Race to the CME Globe bonus.
''I mean, it would be awesome,'' Ko said. ''When you defend something or do something back-to-back, it's always cool to do that.''
Lexi Thompson (67) and Brittany Lincicome (68) were tied for fifth at 10 under, as was France's Karine Icher (68). Second-ranked Inbee Park shaved two shots off her score for the second straight day, shooting 67 to get to 9 under, five shots from the lead and two shots back of Ko.
''We both had really, really good seasons and somebody is going to become 1 and somebody is going to become 2,'' said Park, who's chasing Ko in all those year-end races. ''That's just the way it is. I'm just trying to tell myself I had a really good enough season this year. I've earned what I wanted to earn, what I wanted to achieve. The rest is just a bonus.''
Jang finished with at least a share of the lead for the second straight day. She said the nosebleeds started after a grueling front nine when she made one bogey and one birdie - but still played her final seven holes in 2 under.
''I think the weather is perfect today but my condition is really bad right now,'' Jang said. ''A little headache and little dizzy.''
Weather could play a factor Sunday, with thunderstorms - possibly of the severe variety - in the forecast. That could be the only thing that dampens what players hope will be a frantic finish.
''I think it's great for the tour,'' said Stacy Lewis, who was at 7 under and could win the $1 million bonus if she wins the tournament. ''I think you've got a big purse. Everybody is showing up, everybody is ready to play. It's going to be great TV and theater. That's what you want at the end of the year.''
DIVOTS: Ko will play in a threesome with Thompson and Icher on Sunday, the next-to-last grouping. ... Ko has been listening to Adele's new album to get ready for her rounds at Tiburon this week. ''Anything fun to get me going,'' Ko said. ... Kerr is looking for the 160th top-10, and 18th win of her LPGA career.