Phil Mickelson fired 10 birdies in an eight-under par 64 on Saturday, enough to seize a share of the third-round lead when Vijay Singh bogeyed the last at the BMW Championship.
Fijian veteran Singh, who held a one-shot lead after 36 holes, posted a three-under 69 to join Mickelson on 16-under 200 at Crooked Stick, where 70 players teed it up in the penultimate event of the US PGA Tour's four-tournament playoff series.
Mickelson and Singh, both World Golf Hall of Famers, will have plenty of quality competition on Sunday.
"I'm looking forward to tomorrow's shootout," Mickelson said. "It should be fun."
Northern Ireland's world number one Rory McIlroy, who won his second career major at the PGA championship last month, birdied 18 for a 69 to join Lee Westwood of England on 201. Westwood, a former world number one, carded a 68.
McIlroy leads the playoff standings that will determine the 30 players who advance to the Tour Championships that close the series.
"I'm in great position and excited about tomorrow," said McIlroy, who won the Deutsche Bank Championship last week.
Australian Adam Scott carded a 66 for 202 where he was joined by Dustin Johnson (67) and Robert Garrigus (66).
Tiger Woods was three shots off the lead, alone on 203 after a one-under 71.
"It's an incredible leaderboard," Scott said. "It's going to be fun."