Spaniard Sergio Garcia birdied the final seven holes to match the course record and storm to a three-stroke lead after the second round at the WGC-Bridgestone Invitational in Akron, Ohio on Friday.
The British Open runner-up put on a clinic on the greens, one-putting the final 11 holes for an astonishing nine-under-par 61 on the demanding Firestone Country Club course.
He tied the course record set by compatriot Jose Maria Olazabal in 1990, and his back nine of 27 beat the old record by two strokes.
Garcia posted a 11-under 129 halfway total, while Englishman Justin Rose was in second place on eight-under, followed by Northern Irishman Rory McIlory and Australian Marc Leishman on seven-under.
"I think that was my lowest round in tournament play and also my lowest nine holes," he told Golf Channel.
(Reporting by Andrew Both in Cary, North Carolina, editing by Gene Cherry)