Washington - Daniel Summerhays seized a three-shot lead at the US PGA'S Memorial tournament Saturday as overnight leader Jason Dufner ballooned to five-over par 77 in the third round.
Dufner had started the day with a commanding five-shot lead over Summerhays at Muirfiled Village in Dublin, Ohio.
But Summerhays, in search of a first US PGA Tour title, was tied for the lead after five holes thanks to four quick bogeys for Dufner and his own birdie at the fifth.
Summerhays carded a four-under par 68 for a 13-under par total of 203.
He was three shots clear of Matt Kuchar, who carded a 67 for 206.
Kuchar, the 2014 Memorial champion, is seeking an eighth career PGA Tour win and his first since the Heritage in 2014.
"I drove it really well," Summerhays said. "I had so many good looks at birdie. So many putts were just so close. I really wasn't out of position too much all day.
"Performing under the gun -- it was really fun."
Two-time Masters champion Bubba Watson signed for a 68 and headed a group on 207 that also included Justin Thomas and Dufner -- whose dismal round included a double bogey seven at the par-five 11th and a bogey at the 18th, where the 2013 PGA Championship winner was in the water off the tee.
Summerhays has held at least a share of the 54-hole lead three times on the PGA Tour, but has never gone on to win.
"There will definitely be nerves," he said of the final round. "I'll probably hit a few putts with the hands shaking and everything like that. But it's nothing I haven't experienced before."
He said he'll call on memories of two major championship performances last year -- his tie for eighth at the US Open and his solo third place finish at the PGA Championship.
"Last summer was a big deal for me," Summerhays said. "Playing in the last two or three groups at the US Open, that was probably the most nervous I've ever felt. That and trying to keep my job back in 2011 after my rookie year at Q-School.
"And then coming down the stretch at the PGA Championship last year, having a chance to honestly win until Jimmy (Walker) and Jason (Day) kind of pulled away right at the last minute."
But he'll also be aware of just how treacherous Muirfield Village can be -- as evidenced by Dufner's tough day.
"A trainwreck can happen at any moment," Summerhays said.
Leading third-round scores on Saturday in the US PGA Tour's Memorial tournament in Dublin, Ohio (USA unless noted, par-72):
203 - Daniel Summerhays 66-69-68
206 - Matt Kuchar 69-70-67
207 - Bubba Watson 71-68-68, Justin Thomas 67-71-69, Jason Dufner 65-65-77
208 - Rickie Fowler 70-66-72, Jamie Lovemark 69-69-70
209 - Kevin Streelman 73-69-67, Kevin Kisner 70-69-70, Jordan Spieth 66-72-71
210 - Jason Kokrak 73-67-70, Shane Lowry (IRL) 72-68-70, David Lingmerth (SWE) 65-74-71
211 - James Hahn 74-72-65, Jim Herman 70-74-67, Steve Stricker 74-68-69, Pat Perez 70-72-69, An Byeong-Hun 68-72-71
212 - Ross Fisher (ENG) 73-69-70, Bud Cauley 75-67-70, Charl Schwartzel (RSA) 70-71-71, Phil Mickelson 70-70-72, Kyle Stanley 74-67-71, Marc Leishman (AUS) 70-70-72, Lucas Glover 67-73-72, Emiliano Grillo (ARG) 71-68-73