Tiger Woods blitzed the field with a scintillating second round of 62 to take a two-shot lead at the halfway point of his own Northwestern Mutual World Challenge tournament.
The World No.1, who plays host at the Sherwood Country Club, tied the course record with a flawless performance that saw him rack up ten birdies, five on the front and five on the back nine.
It saw the 37-year-old surge to the top of the leaderboard at 11-under-par, two clear of his nearest challenger, and overnight leader, Zach Johnson.
Woods' day-two efforts were a far cry from his opening round, which began with a bogey on the first before he made gains at five and 11.
Twenty-four hours on he kicked off with a birdie at the first, repeating the trick on the second hole before picking up further shots at five, seven and eight.
The birdies continued after the turn as he made more progress at 10, 11, 13, 14 and 16, before a pair of pars finished off a blemish-free round.
Johnson two back
Johnson (68) looked in similarly sweet form as he birdied three of the first five holes, but he parred the next 12 before picking up an extra stroke at the 18th to put him clear in second.
Matt Kuchar was a shot behind on eight-under, while defending champion McDowell moved into fourth place, improving vastly on his level-par first round with a fine 67.
While four bogeys hampered the Northern Irishman on Thursday, he was bogey-free second time around with five birdies moving him up the field, one clear of Bubba Watson.
Ian Poulter, four-over after his first round, improved vastly as a 67 put him one-under overall, but compatriot Lee Westwood was five-over after following his opening 74 with a 75.
However, there was worse news still for Rory McIlroy whose five-over 77 left him joint 16th in the 18-strong field at six-over.
The Northern Irishman struggled all day, with a double-bogey at the fourth and further dropped shots at the eighth, 12th, 13th and 14th, but the low point came with a quadruple-bogey nine at the par-five 16th.
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