Brooks Koepka leads rain-soaked US PGA Championship

For the second time in as many months, Brooks Koepka is on the cusp of a fifth major win.

The American fired a second consecutive four under 66, enough to move him to six under for the tournament, one ahead of Canadian Corey Conners and Viktor Hovland of Norway.

Conners had led on seven under par after recording two birdies and 13 pars in his first 15 holes, only to find sand off the tee on the 16th and then drill his second shot into the face of the bunker.

That led to a double bogey six and with Hovland dropping a shot on the 18th to also finish five under, Koepka enjoyed the outright 54-hole lead for the second consecutive major.

Koepka felt he "choked" away the Masters last month having been four ahead of eventual winner Jon Rahm when play was suspended due to bad weather in the third round.

"I won't do it again the rest of my career... I promise I won't show up like that on Sunday," he told the press.

"I was just told that I think only Tiger and Jack have won three (US PGA titles), so that would be pretty special to be in a list or category with them."

Bryson DeChambeau, who played alongside Koepka at Oak Hill on Saturday and was roundly booed on the first tee, returned a 70 to lie three shots off the lead.

Meanwhile, Rory McIlroy followed two early birdies with three bogeys in the space of four holes from the sixth, but rallied to cover the back nine in 33 to keep Koepka in his sights.

The 34-year-old has struggled with his long game all week and revealed on Thursday he was also battling an unspecified illness.

"I'd obviously like to be a couple of shots closer to the lead," said the world number three.

"But I think with how I've felt this week, if you had have told me on Thursday night that I'd be going into Sunday in the top five and with a realistic chance to win this golf tournament, I would have taken it."

READ MORE: 'Start off hot and we'll see' - Tommy Fleetwood eyes US PGA Championship glory