South Korea's Kim In-kyung did her best to keep pace with a 68 but found herself trailing in second place after Korda's impressive finish.
"When you end on a birdie, you're just really excited to play the next day and get it doing, so I'm definitely excited," said Korda, who is playing in her 19th LPGA event and first Marathon Classic.
"My mentality hasn't changed. It's the same as the first two days. I just try to take it shot by shot really."
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Korda is trying to join older sister Jessica Korda as an LPGA winner. Only one set of sisters have both won LPGA events -- Annika Sorenstam (72 career wins) and Charlotta Sorenstam (one career win). Jessica Korda has four LPGA victories.
The Korda sisters have a famous father -- former grand slam tennis champion Petr, who won the 1998 Australian Open.
The younger Korda started her rookie campaign in style with a second-place finish at the Pure Silk Bahamas LPGA Classic.
"I've learned a lot my rookie year out here," Korda said.
"It's definitely a key to stay patient and really to take it shot by shot. I've been in a couple positions where I've been on top of the leaderboard, and I just really got ahead of myself, started thinking too far ahead, and I just told myself I need to calm down really, take it shot by shot and stay calm, breathe a little bit more and just stay calm."
Gerina Piller, the leader after each of the first two rounds, carded a 70 on Saturday to fall into a tie for third at 12 under with U.S. Women's Open champion Park Sung-hyun (67), Lexi Thompson (69), Sandra Changkija (65), tour rookie Aditi Ashok (68) of India and Taiwan's Peiyun Chien (69).
(Editing by Andrew Both)
