Defending champion Seo Hee-kyung shot a four-under-par 68 to claim a one-stroke lead after the first day of the Korean Ladies Masters.

Seo carded five birdies against just one bogey at Cypress Golf and Resort to move ahead of compatriots Sarah Lee, Kim Hyun-ji, Lee Bo-mee and Australian Anna Rawson.

"I have gained more confidence since last year because this year I have won four more tournaments," said Seo. "I feel my game is in good shape."

European number three Becky Brewerton, the top-ranked player at the event, was in a tie for 15th at one over.