One more round in the 60s at the Founders Cup is all Jin Young Ko needs to join Annika Sorenstam in the LPGA Tour record book.

That might be all it takes to win the Founders Cup, too.

Ko picked up her fourth birdie on the par-5 16th and closed with two pars for a 2-under 69, giving her a four-shot lead at Mountain Ridge as she tries to win for the third time this year.

Major winners Minjee Lee (2-over 73) and Hannah Green (1-under 70) are best of the Australian contingent at 3-under with Su Oh (73, even) and Katherine Kirk (72, 1-over) further back.

Saturday was another great day for Ko, who since July has recorded two victories, a runner-up and three other top 10s in her past six events.

Saturday was the 26-year-old's 13th consecutive round in the 60s, one off the LPGA record Sorenstam set during a four-tournament stretch in 2005.

Ko played bogey-free on the back nine and stretched her lead to four shots over US Women's Open champion Yuka Saso (67), Elizabeth Szokol (65), two-time major champion So Yeon Ryu (71) and Lindsey Weaver (69).

Ko was at 13-under 200 as she tries to match Nelly Korda as the only three-time winners on the LPGA Tour this season.

Korda, who also won the Olympic gold medal, replaced Ko at No.1 in the world in late June by winning her first major at the KPMG Women's PGA Championship.

The 23-year-old American, who is back in action this week after a month off, had a 68 on Saturday and was in a large group tied for sixth at 7-under 206 that included Maria Fassi, Caroline Masson and Lexi Thompson.

What motivates Ko as much as anything is going home - with the lone Asia event on the LPGA Tour to come in a fortnight in South Korea.

"I don't want to think about win," Ko said.

"Just think about my swing or my putting. And I will have fun with my caddie, Dave Brooker.

"And yeah, after tomorrow I will go back to Korea. So that's going to be motivation for me."