Tiger Woods stormed into the lead at his own Northwestern Mutual World Challenge tournament as a 10-under par second round of 62 put him two clear of overnight leader Zach Johnson.
Woods, who plays host at the Sherwood Country Club, took full advantage of the birdie opportunities that came his way to tie his own course record and move to 11-under-par overall.
Behind him there were encouraging signs from Ireland's Graeme McDowell, but compatriot Rory McIlroy had a day to forget with a five-over 77.
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 Woods kicked off with a birdie at the first, repeating the trick on the second hole before further gains at five, seven and eight.
The birdies continued after the turn as he picked up shots at 10, 11, 13, 14 and 16, before a pair of pars finished off a blemish-free round.
Johnson looked in similarly sweet form as he birdied three of the first five holes, but he parred the next 12 there 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 by going five under.
While four bogeys hampered him on Thursday, he was blemish-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.
There was worse news still for McIlroy whose five-over 77 left him joint 16th in the 18-strong field.
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 at the 16th.