With his four-shot win in the CJ Cup in South Korea, Brooks Koepka has ascended to world No.1 for the first time, leap-frogging Dustin Johnson in the process.

Koepka, 28, closed with a 64 at Nine Bridges to win his fifth career PGA Tour title and add another chapter to what has been a roller-coaster 2018.

After wrist surgery forced him to miss most of the first four months of the year, he came back to successfully defend his US Open title at Shinnecock Hills, becoming the first player since Curtis Strange in 1989 to win the championship in consecutive years. The US PGA Championship at Bellerive in August gave him major win No.3.

He made his second Ryder Cup appearance at Le Golf National last month, where an errant tee shot on the opening morning lefta female fan blind in one eye. He also subsequently denied reports of a fight between he and good friend Dustin Johnson in the aftermath of the USA’s heavy defeat.

All that was before he was named the PGA Tour Player of the Year two weeks ago.

• Who is Brooks Koepka's caddie?

Now, he’s the world’s top golfer.

Koepka is the 23rd different player to top the rankings and the eighth American. He is also the fourth different player to hold the top spot in 2018, following Johnson, Justin Thomas and Justin Rose.