Pinehurst - Martin Kaymer posted the lowest 36-hole score in US Open history on Friday, firing his second consecutive five-under par 65 to seize a six-stroke lead after two rounds at Pinehurst.
The 29-year-old German's bogey-free day left him on 10-under par 130, matching the best 36-hole start in major golf history.
Kaymer erased the old 36-hole Open mark of 131 set by Rory McIlroy in 2011 on his way to winning his first major title at Congressional.
No player in major golf history had ever gone as low as 65 in each of the first two rounds.
"Somebody has to do it at one stage," Kaymer said. "You need to play very solid and you need a little bit of luck here or there."
The only prior players to score 130 in the first two rounds of a major were England's Nick Faldo and American Brandt Snedeker, who each opened on 66 and followed with 64 at the British Open, Faldo in 1992 at Muirfield and Snedeker at Lytham in 2012.
"It's just very satisfying," Kaymer said. "The way I worked my way around the course, I hit some smart shots and didn't play too aggressive. I didn't make many mistakes."
Kaymer's six-shot edge on second-place American Brendon Todd matched the largest 36-hole lead in US Open history -- those enjoyed by Tiger Woods on his way to victory at Pebble Beach in 2000 and by McIlroy in 2011.
"Martin played exceptionally well," Todd said. "If he comes back to us, great. If he shoots 10-under again in the next two days, then he's superhuman."
Americans Kevin Na and Brandt Snedeker shared third on 137 with Zimbabwe's Brendon de Jonge, Sweden's Henrik Stenson and Americans Keegan Bradley, Dustin Johnson and Brooks Koepka another shot adrift.
"It's going to be tough to catch him," Na said. "It's unbelievable what he's done. It's amazing. He looks flawless."
Kaymer, the 2010 PGA Championship winner, is coming off a Players Championship victory last month that ended a three-year PGA win drought and bolstered his confidence even before he shot the low round both days, another US Open first, and threatened to become just the seventh wire-to-wire Open winner.
"I didn't make a bogey which is nice," he said. "I got tired the last three or four holes, but I didn't make any mistakes. Didn't miss many fairways. Didn't miss many greens."
Kaymer, who began at the par-5 10th hole, opened with a six-foot birdie putt, added a 20-foot birdie putt at 13 plus a 25-footer at 16 and four-foot birdie putts at the third and fifth and a key par save at seven, the lone hole where he made bogey on day one.
"He's as dialed in as I've seen," said Bradley. "He's steady and doesn't seem to get too down. That's a good combination for a US Open."
Kaymer is far from complacent, aware that difficult conditions are a trademark of US Opens and disaster could lurk over the last two rounds.
"It's not a done deal," Kaymer said. "You don't approach Saturday and Sunday in a relaxed way. On Sunday afternoon when you lift the trophy you can relax. You have to keep playing well."
Reigning British Open champion Phil Mickelson, a six-time US Open runner-up seeking a victory to complete a career grand slam, struggled to a 73 to share 33rd, 13 strokes back.
"I feel like I'm playing well enough to win the US Open, except for putting," he said. "After I've 3-putted three or four times, I lose my focus on the other stuff. It really affects my ability to concentrate and my momentum and energy. It's a frustrating time."
Mickelson resumed his regular putting grip after a one-day claw grip experiment, saying, "I don't feel like the stroke is bad but I'm just not dialed in. I'm just not making them."
Two-time major winner McIlroy and Masters runner-up Jordan Spieth were among those on 139, with world number one Adam Scott and Japan's Hideki Matsuyama 10 off Kaymer's pace.
"Potentially, he goes out tomorrow and plays better than everyone again and this thing's over," Scott said. "If he does it for two more days, then we're all playing for second spot.
"I'm going to have to play a couple of exceptional rounds to have a chance."
Defending champion Justin Rose and Aussie Jason Day were on 141.
"I think 10-under is unbelievable golf," Rose said. "He has been strong under pressure."
Kaymer has four wins and two runner-up efforts in seven events he has led after 36 holes.
"I still feel like I'm in the tournament," Rose said. "It's by no means over at this stage. One of us could shoot 65-65 on the weekend."
It won't be reigning Masters champion Bubba Watson, who missed the cut on 146.
Results on Friday after the second round of the 114th US Open Golf Championship at par-70 Pinehurst:
130 - Martin Kaymer (GER) 65-65
136 - Brendon Todd (USA) 69-67
137 - Kevin Na (USA) 68-69, Brandt Snedeker (USA) 69-68
138 - Brooks Koepka (USA) 70-68, Dustin Johnson (USA) 69-69, Brendon De Jonge (ZIM), 68-70, Keegan Bradley (USA) 69-69, Henrik Stenson (SWE) 69-69
139 - Matt Kuchar (USA) 69-70, Rory McIlroy (NIR) 71-68, Chris Kirk (USA) 71-68, Jordan Spieth (USA) 69-70
140 - Adam Scott (AUS) 73-67, Francesco Molinari (ITA) 69-71, Erik Compton (USA) 72-68, Ian Poulter (ENG) 70-70, Hideki Matsuyama (JPN) 69-71, Rickie Fowler (USA) 70-70
141 - Steve Stricker (USA) 70-71, JB Holmes (USA) 70-71, Danny Willett (ENG) 70-71, Marcel Siem (GER) 70-71, Jason Day (AUS) 73-68, Justin Rose (ENG) 72-69, Aaron Baddeley (AUS) 70-71
142 - Jimmy Walker (USA) 70-72, Victor Dubuisson (FRA) 70-72, Noh Seung-Yul (KOR) 70-72, Fran Quinn (USA) 68-74, Lucas Bjerregaard (DEN) 70-72, Graeme McDowell (NIR) 68-74
143 - Garth Mulroy (RSA) 71-72, Jim Furyk (USA) 73-70, Gary Woodland (USA) 72-71, Daniel Berger (USA) 72-71, Scott Langley (USA) 72-71, Patrick Reed (USA) 71-72, Webb Simpson (USA) 71-72, Phil Mickelson (USA) 70-73, Billy Horschel (USA) 75-68, Kenny Perry (USA) 74-69, Shiv Kapur (IND) 73-70
144 - Alex Cejka (GER) 73-71, Bill Haas (USA) 72-72, Stewart Cink (USA) 72-72, Harris English (USA) 69-75, Ernie Els (RSA) 74-70, Louis Oosthuizen (RSA) 71-73, Retief Goosen (RSA) 73-71, Bo Van Pelt (USA) 72-72, Kevin Tway (USA) 72-72, Cody Gribble (USA) 72-72, Ryan Moore (USA) 76-68, Sergio Garcia (ESP) 73-71, Boo Weekley (USA) 71-73, Matthew Fitzpatrick (ENG) 71-73, Russell Henley (UA) 70-74, Clayton Rask (USA) 73-71
145 - Kevin Stadler (USA) 77-68, Justin Leonard (USA) 75-70, Paul Casey (ENG) 70-75, Toru Taniguchi (JPN) 72-73, Zac Blair (USA) 71-74, Zach Johnson (USA) 71-74, Billy Hurley (USA) 71-74, Nicholas Lindheim (USA) 72-73,
Missed the cut
146 - Casey Wittenberg (USA) 74-72, Andres Echavarria (COL) 74-72, Hudson Swafford (USA) 76-70, Mark Wilson (USA) 70-76, Shane Lowry (IRL) 73-73, Luke Donald (ENG) 77-69, Bubba Watson (USA) 76-70, Charl Schwartzel (RSA) 70-76, Jason Dufner (USA) 72-74, Hunter Mahan (USA) 74-72, Rod Pampling (AUS) 73-73, Cory Whitsett (USA) 77-69, Hunter Stewart (USA) 75-71, Lee Kyoung-Hoon (KOR) 74-72, Matt Jones (AUS) 74-72, Angel Cabrera (ARG) 74-72, Miguel Angel Jimenez (ESP) 72-74, Thongchai Jaidee (THA) 73-73, Joost Luiten (NED) 70-76, Matt Dobyns (USA) 74-72, Brian Campbell (USA) 76-70
147 - Ken Duke (USA) 75-72, John Senden (AUS) 71-76, Nicolas Colsaerts (BEL) 72-75, Darren Clarke (NIR) 75-72, Geoff Ogilvy (AUS) 73-74, Ryan Blaum (USA) 73-74, Luke Guthrie (USA) 73-74, Jim Renner (USA) 74-73, Chris Doak (SCO) 74-73, Andrea Pavan (ITA) 75-72, Stephen Gallacher (SCO) 73-74, David Toms (USA) 73-74
148 - Lucas Glover (USA) 79-69, Ryan Palmer (USA) 74-74, David Gossett (USA) 76-72, Sam Love (USA) 76-72, Cameron Wilson (USA) 78-70, Chad Collins (USA) 74-74, Brian Stuard (USA) 75-73, Matt Every (USA) 76-72, Roberto Castro (USA) 74-74, Lee Westwood (ENG) 75-73, Nick Watney (USA) 76-72, Liang Wen-Chong (CHN) 74-74, Justin Thomas (USA) 75-73
149 - Oliver Fisher (ENG) 74-75, Joe Ogilvie (USA) 73-76, Henrik Norlander (SWE) 70-79, Pablo Larrazabal (ESP) 71-78, Tom Lewis (ENG) 79-70, Craig Barlow (USA) 74-75, Smylie Kaufman (USA) 73-76
150 - Niclas Fasth (SWE) 76-74, Graham DeLaet (CAN) 75-75, Bernd Wiesberger (AUT) 72-78, Kim Hyung-Sung (KOR) 73-77, Kevin Sutherland (USA) 75-75, Max Kieffer (GER) 76-74, Maverick McNealy (USA) 74-76, Anthony Broussard (USA) 78-72
151 - Graeme Storm (ENG) 72-79, David Oh (USA) 75-76, Y.E. Yang (KOR) 75-76, Jamie Donaldson (WAL) 71-80, Brett Stegmaier (USA) 77-74, DA Points (USA) 77-74, Brady Watt (AUS) 77-74
152 - Steve Alker (NZL) 76-76, Kevin Streelman (USA) 75-77, Gonzalo Fernandez-Castano (ESP) 76-76, Simon Griffiths (ENG) 72-80, Rob Oppenheim (USA) 75-77, Kevin Kisner (USA) 75-77, Robert Allenby (AUS) 79-73, Aron Price (AUS) 78-74
153 - Jonas Blixt (SWE) 77-76, Jeff Maggert (USA) 73-80, Robby Shelton (USA) 78-75, Nick Mason (USA) 78-75
154 - Chris Thompson (USA) 80-74, Oliver Goss (AUS) 71-83
155 - Bobby Gates (USA) 79-76, Donald Constable (USA) 82-73, Brandon McIver (USA) 82-73
157 - Will Grimmer (USA) 77-80
159 - Andrew Dorn (USA) 79-80
160 - Azuma Yano (JPN) 77-83
162 - Kiyoshi Miyazato (JPN) 81-81