Koepka in control in South Korea, on track to become world number one

Brooks Koepka is on track to become world number one after opening up a four-shot lead at The CJ Cup at Nine Bridges on Saturday.

The American three-time major champion moved into 13 under at Jeju Island, South Korea after shooting a five-under 67 in the third round.

Koepka is well-placed to secure a fifth PGA Tour win, which would guarantee him the world number one ranking for the first time in his career.

The 28-year-old holed five birdies – including two to finish – and no bogeys during his third round, taking complete control of the event.

Scott Piercy (72) and Ian Poulter (68) are Koepka's nearest challengers, sitting at nine under.

A group of six players are a shot further back, including Rafa Cabrera Bello, who surged into contention with a seven-under 65.

The Spaniard is joined by Cameron Smith (67), Jamie Lovemark (68), Pat Perez (68), Gary Woodland (68) and Chez Reavie (70) in a tie for fourth.

Jason Day enjoyed a strong round with a seven-under 65, but the Australian appears too far back at seven under.

Justin Thomas, the winner of the inaugural event last year, has been unable to get going, an even-par 72 leaving him at one under.