Jim Furyk, seeking a second playoff crown and Tour Championship title in three years, birdied seven of the first 10 holes to grab the lead after two rounds of the $8 million PGA event.
The 42-year-old American, who has not won since capturing this crown in 2010, on Friday fired a six-under par 64 to stand on seven-under 133 after 36 holes in the 30-man showdown to determine the US PGA season playoff champion.
Some have questioned USA skipper Davis Love's decision to include Furyk on the Ryder Cup team, which will square off against the Europeans next week in Chicago.
But the former US Open winner believes his record speaks for itself and he has nothing to prove.
"Look at the way I play golf -- the way I swing the golf club and grip the putter," he said. "Look at the way I go about my business. I don't hit the ball very far. I'm short.
"If I really cared what the critics thought the last 19 years, I really wouldn't be here.
"My teammates know that I'm going to give 110 percent. They know I have a lot of heart. I have a lot of grit, and that's what I'm going to do.
Furyk led by one stroke over England's Justin Rose, with Americans Bubba Watson and Bo Van Pelt two off the pace and Americans Dustin Johnson and Matt Kuchar three shots adrift.
Former World No. 1 and 14-time major champion Tiger Woods, who shared the lead with Rose after the first round, fired a 73 to stand on 139 after the second round.
Furyk, who failed to qualify for last year's playoff finale, opened the front and back nines with birdies and sizzled in between, sinking three birdies in a row starting at the par-4 third and adding two more at the par-4 seventh and par-5 ninth.
Furyk struggled into the clubhouse with bogeys at the 13th, par-5 16th and par-3 18th while mixing in birdies at the par-5 15th and par-4 17th to keep himself atop the leaderboard.
Every man in the field has a chance to claim the $10 million playoff crown and some can do it without winning the tournament title depending on where other players finish.
Based on current placings, Furyk would finish second to World No. 1 Rory McIlroy, who won two prior playoff series events as well as his second major title at last month's PGA Championship.
Northern Irishman McIlroy, one of five players who can take the playoff crown with a victory no matter where anyone else finishes, fired a 68 to stand in a share of seventh on 137 with Americans Zach Johnson and Robert Garrigus.
McIlroy birdied the par-3 sixth, took a bogey at the par-4 14th but answered with an eagle at the par-5 15th.
"I just have to try to think of my standing in this golf tournament, not really think about anything else," McIlroy said.
Woods, also among the five who can win the bonus by winning the event, began with a bogey, responded with a birdie at the third then sandwiched birdies at the seventh and ninth around a double bogey at the par-4 eighth.
After bogeys at the 11th and 12th, Woods birdied the 13th but stumbled again with bogeys at 16 and 17.
"I didn't play very good today. Didn't hit it very good, and definitely didn't putt well," Woods said. "So it was a struggle all day."
Watson, the reigning Masters champion, and Rose, who shared the lead with Woods after day one, made back-nine charges after so-so starts.
Rose sandwiched bogeys at the sixth and eighth around a birdie at the seventh, then fired back-to-back birdies on 11 and 12 and added another at the par-5 15th, then answered a bogey at 17 with a closing birdie.
Watson went birdie-bogey to begin his round, then began the back nine with a birdie and added another at the 13th and back-to-back birdies at 16 and 17.
Van Pelt had back-to-back birdies at the third and fourth holes, then back-to-back bogeys at the fifth and sixth. He charged with four birdies in a row starting on the par-4 eighth but stumbled with bogeys at 15, 16 and 18 with only a birdie at the 17th to avoid a worse fall from Furyk's heels.