Local hope An Byeong-hun holds a one-shot lead after round one of the CJ Cup.

The South Korean shot an eight-under 64 on the opening day at Nine Bridges to hold a slender lead over Chilean Joaquin Niemann, with Australian Jason Day one stroke further back.

Americans Charley Hoffman and Charles Howell III are among the chasing pack at five-under, having spent most of the day challenging at the top of the leaderboard.

Defending champion and world number one Brooks Koepka had something of a frustrating round but nailed an eagle on the 18th to finish at three-under.

The opening day belonged to An, though, as he finished with eight birdies – including four on the back nine – to move into the lead.

Only Niemann bettered An’s run at the back end of Nine Bridges with five birdies, including two on holes 17 and 18.