He needed to pick up two shots in the last three holes for an elusive sub-60 round, but parred his way home and then joked: “I choked.”
“It doesn’t get much better than that,” said Koepka, who turned 23 on Friday. “It was flawless golf. That run I got on from the ninth, I just holed everything. I was hitting it so close; I didn’t have a putt outside 15 feet.
“I’ve still got to go out there and play 18 holes tomorrow and I can’t think about winning yet. Someone could have a round like I did today and force me to do something. I’ll be taking the same approach as I’ve had all week; there’s no point playing defensively.”
Koepka, who qualified for last year’s US Open Championship, added: “I might be American but right now I see my future in Europe. The goal is to get a European Tour car for next season and I would love to do that. In time I might go back to the States, but right now I’m loving life on the Challenge Tour.”
Domingo and Espana - themselves three shots clear of the rest of the field - will have to produce something special on Sunday to prevent Koepka winning his second Challenge Tour title.
Domingo said: “Almost everything was perfect today. Obviously Brooks is far ahead but you never know in golf and the only thing I can do is play my best and see where I end up.”
Espana, who only turned professional in January and is playing this week courtesy of a sponsor’s invitation, added: “I found something with my putting on the back nine today so hopefully I can continue that tomorrow and finish as high up as I can. I won’t have many opportunities this year as I am relying on invites, so it’s important that I take my chances.”