LOUISVILLE — After Rory McIlroy successfully sloshed his way around rain-soaked Valhalla in the second round of the 96th PGA Championship on Friday, he was asked what made him such a good mudder.
"What's a mudder?" the 25-year-old Irishman asked.
McIlroy may not know horse lingo, but he knows his golf game is up to any challenge in any weather.
Seeking his second major title in two months and the fourth of his career, McIlroy followed a first-round 66 with a 67 on Friday to lead the PGA going into the weekend.
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"When I'm playing like this, it's obviously very enjoyable," he said. "I can't wait to get back on the course again tomorrow and do the same thing all over again."
McIlroy is on quite a roll. He won his previous two outings — the British Open and Bridgestone Invitational — and counting his 9-under par here, he's 41-under in his last 10 rounds.
His closest pursuers are Jason Day and Jim Furyk, who are one shot behind.
Day, a 26-year-old Australian, fired Friday's best round — a 65. Furyk, 44, was runner-up in last year's PGA.
Ryan Palmer, Rickie Fowler and Mikko Ilonen are 7-under. Phil Mickelson eagled the 18th hole to finish 6-under.
McIlroy might be difficult to catch because he intends to keep his foot on the gas.
"If I'm two ahead, I'm going to try to get three ahead. If I'm three ahead, I'm going to try to get four ahead. And if I'm four ahead, I'm going to try to get five ahead.
"I'm going to try to keep the pedal down. That's my mindset whenever I'm leading a golf tournament."
Has he ever eased off the accelerator?
"I went protection mode once in my career, and it was the 2011 Masters. That didn't work out very well," he said referring to the disaster that befell him at Augusta. He led by four before collapsing with a final-round 80.
McIlroy didn't play flawless golf Friday. He had a couple bogeys when he failed to get up and down from bunkers.
But whenever he made a misstep, he didn't let it affect him. He closed out his first nine with a 25-foot eagle on the par-5 18th, then finished the day with birdies on two of his last three holes.
U.S. Open champ Martin Kaymer, who played with McIlroy the last two days, has been impressed.
"He hits the driver that straight and that long, and the short game is incredible. It's very difficult to beat him," Kaymer said. "He's definitely the best player in the world."
Day birdied the last two holes to earn a share of second place and a Saturday pairing with McIlroy.
Day's best shot of the day was a 250-yard 1-iron that set up a 10-foot eagle at No. 7.
Day said there's no mistaking who's the favorite going into the weekend.
"With how Rory is playing ... he's hitting the ball longer and straighter than pretty much everyone in the field.
"With how he's playing, he could run away with things. I'm going to hopefully try and keep pace."
Furyk is a veteran in the majors. He won the 1997 U.S. Open, and has 20 other top-10 finishes. He was fourth in last month's British Open.
Palmer, like McIlroy, had to play through nasty early-morning weather. He should have even begun play in the wet conditions.
Palmer's opening drive found water in the fairway, "and when we got to the green, sure enough, there was casual water all over it.
"They said that's just golf. We're like, 'Tell the guy indoors making that decision to come check it out because it's wet."
Fowler has been strong in all the majors this year. He tied for fifth at the Masters and tied for second at the U.S. Open and British Open.
He fired a 5-under 66 Friday to get in contention again. "It's been fun in the majors this year, and I'm excited for the weekend."
Lee Westwood, the first-round leader, was within one shot of the lead before a double bogey at the 13th sent him sliding down the leaderboard. He carded two more bogeys before salvaging a birdie at the 18th. He finished 1-over for the day, 5-under for the tournament.
Even though there are two days left in the title chase, the media couldn't resist asking McIlroy to speculate about winning again.
"It would be big," he said. "My fourth major championship, two in one year, and two in a row.
"There's a lot of golf left to be played, and I'm going to try my best to keep what I've got and keeping doing that.
"If I'm sitting here Sunday night with the Wanamaker Trophy, I'll be very happy."