A day after both Justin Thomas and Jason Kokrak equalled the Medinah course record, Hideki Matsuyama broke it by two shots with an astonishing nine-under-par 63.
In doing so, the 27-year-old Japan player also took the BMW Championship lead after round two.
Matsuyama hit nine birdies and no bogeys to move to 12-under overall, one shot in front of Americans Patrick Cantlay and Tony Finau.
“It seemed like every birdie chance I had I made the putt,” Matsuyama told reporters.
Thomas shot a three-under 69 to move to 10-under overall, but fellow overnight leader Kokrak had a less successful day and fell back to six under after a one-over 73.
After going around in 66, England’s Tommy Fleetwood moved up to eight under alongside Northern Ireland’s Rory McIlroy, who shot 67. McIlroy is four strokes off the lead after a second round which included six birdies and a single dropped shot.
British Open champion Shane Lowry is currently propping up the leaderboard on two over par after rounds of 72 and 74, while Graeme McDowell is on three under after following his opening 69 with a 72.
Tiger Woods’s form remains inconsistent, getting five birdies but also four bogeys in a second consecutive round of 71.
Brooks Koepka also scored a 71, moving the world number one to five under overall.
England’s Justin Rose shot a 73 and fell back to three under, one behind his compatriots Paul Casey and Ian Poulter.
Collated second round scores & totals in the USPGA Tour BMW Championship, Medinah CC (USA unless stated, par 72):
132 Hideki Matsuyama (Jpn) 69 63
133 Tony Finau 67 66, Patrick Cantlay 66 67
134 Justin Thomas 65 69
135 Rory Sabbatini (Svk) 67 68, Xander Schauffele 67 68, Lucas Glover 66 69, Adam Hadwin (Can) 67 68, Corey Conners (Can) 69 66, Chez Reavie 67 68
136 Rory McIlroy (NIrl) 69 67, Tommy Fleetwood (Eng) 70 66, Kevin Tway 69 67, Kevin Kisner 68 68
137 Joel Dahmen 66 71, Max Homa 70 67, Jon Rahm (Spa) 68 69, Rickie Fowler 67 70, Brandt Snedeker 66 71, Si Woo Kim (Kor) 70 67
138 Jason Kokrak 65 73, Adam Scott (Aus) 67 71, Jim Furyk 66 72, Cheng-Tsung Pan (Tai) 71 67
139 Brooks Koepka 68 71, Joaquin Niemann (Chi) 74 65, Louis Oosthuizen (Rsa) 70 69, Cameron Champ 71 68, Patrick Reed 68 71, Charles Howell III 70 69
140 Andrew Putnam 71 69, Ryan Palmer 68 72, Scott Piercy 67 73, J.B. Holmes 69 71, Abraham Ancer (Mex) 68 72, Collin Morikawa 67 73, Ian Poulter (Eng) 70 70, Paul Casey (Eng) 70 70, Ryan Moore 71 69
141 Jason Day (Aus) 70 71, Graeme McDowell (NIrl) 69 72, Byeong-Hun An (Kor) 71 70, Matt Kuchar 71 70, Justin Rose (Eng) 68 73, Dylan Frittelli (Rsa) 72 69, Rafael Cabrera-Bello (Spa) 69 72, Jordan Spieth 70 71
142 JT Poston 68 74, Tiger Woods 71 71, Sung Kang (Kor) 69 73, Webb Simpson 70 72, Emiliano Grillo (Arg) 72 70, Dustin Johnson 70 72, Wyndham Clark 69 73, Adam Long 72 70, Bryson DeChambeau 71 71, Sungjae Im (Kor) 70 72
143 Phil Mickelson 70 73, Keegan Bradley 69 74, Vaughn Taylor 73 70, Marc Leishman (Aus) 72 71, Gary Woodland 70 73
144 Billy Horschel 71 73
145 Francesco Molinari (Ita) 72 73, Nate Lashley 72 73, Troy Merritt 69 76
146 Harold Varner III 72 74, Shane Lowry (Irl) 72 74, Keith Mitchell 72 74
