US Open champion and world No.2 Dustin Johnson fired a Crooked Stick course record to surge into a tie for the lead at the BMW Championship.
Johnson carded a bogey free nine-under-63 thanks to five birdies and two eagles to rocket up to 14-under for the tournament.
He joins first round leader Roberto Castro (65) at the top of the leaderboard in the penultimate US PGA Tour playoff event with the American duo enjoying a three-shot buffer over the nearest chaser.
"Everything was working well obviously," Johnson said.
"I putted well, any time you shoot that good a score you putt really well and I putted really well today.
"I drove it good, hit a lot of good iron shots, but I really rolled the putter nicely."
World No.6 Adam Scott put together a second consecutive three-under 69 to remain the best of the Australians but at six-under he sits eight shots back in a tie for 10th.
"I played decent golf but I need to play exceptional this weekend to have a chance," Scott said.
World No.1 Jason Day rebounded from his poor opening round with a 67 but at four-under he is 10 shots adrift and in need of a weekend miracle.
"Nice to turn it around and hopefully I can put together something similar this weekend and climb up the leaderboard," Day said.
Importantly both Australians remain projected to be in the top five of the season long points race as the battle for the 30 spots in the season ending Tour Championship heats up.
Those inside the top five heading to Atlanta can guarantee the FedExCup, and the $US10 million ($A13.09 million) bonus, should they win the Tour Championship.
The season is effectively over for Aaron Baddeley and Marc Leishman.
The pair needed to finish in the top three to advance but with Baddeley 12 shots off the pace and Leishman a distant 19 shots back it would take a miracle for either to survive.
