Duval, who attended college at nearby Georgia Tech, carded five birdies and three bogeys on Friday for a second-round 68 to move to 7-under-par through 36 holes, one shot clear of Woods and Chris Perry at the East Lake Golf Club in Atlanta, Ga.
Woods, paired with Perry in the second round, started slowly, but fought back for a 4-under-par 66 to tie his Friday playing partner, who shot 65, for second place. Vijay Singh and Paul Azinger are tied for fourth place at 5-under. First-round leader Ernie Els is now three shots off the pace at 4-under-par, tied with David Toms and Phil Mickelson in sixth position.
Thursday, Els posted a bogey-free 64. Friday, the South African carded a birdie-free 72. Els managed 16 pars and two bogeys in the second round.
'Sometimes, it's hard when you go for a great score to go out there and find it again,' said Els. 'I was trying to force the issue. It starts to get to you a little bit when you can't get your swing going. But that's golf.'
For most, Friday proved to be a struggle down the stretch. Mickelson was 7-under for the tournament through 15 holes, before finishing double bogey-par-bogey for a round of 1-under-par 69. Likewise, Perry made his way to 7-under-par, until a bogey 4 at the last dropped him into a tie for second.
Duval also dropped a shot coming home, bogeying the par-4 17th. However, the 2000 Buick Challenge champion's round could have been worse had it not been an unsuspecting birdie at the par-5 15th.
Coming off birdies at the 13th and 14th holes, Duval placed his tee shot at the 15th in prime position down the middle of the fairway. However, when the world's No. 3- ranked player approached his ball, he found a clump of mud covering his Titleist. Duval's second shot came squirting off his clubhead, straight into the right rough. From there, Duval could do no better than the greenside bunker, where he holed out for an unorthodox birdie 4.
'I didn't come here thinking that I have to just beat Tiger,' Duval said. 'If you get caught up competing against one player, you're not going to win golf tournaments that you maybe should.'
While many were trying to keep their Friday rounds from unraveling coming home, Tiger found trouble right from the start. Woods bogeyed two of his first five holes in the second round - this from a man who went 110 straight holes without a negative number.
But just when it looked like Tiger' streak of 40-consecutive sub-par rounds was in jeopardy, the world's top player birdied the 7th, 9th, 11th and 14th holes.
He wasn't done.
Tiger eagled the par-5 15th to move to 6-under-par for the tournament, momentarily tying him for the lead. His third bogey of the day dropped him back to 5-under, yet once again, Woods responded in typical-Tiger fashion by carding his final birdie of the day at the 17th.
'I'm right back in the tournament,' said Woods, who is trying to join Byron Nelson, Sam Snead and Ben Hogan as the only men to win 10 Tour events in one season.
'It'll be fun to play with my partner (at the World Cup),' Tiger added.
'He's the standard right now by which you're comparing your golf,' Duval said of Woods. 'I want to go out and play good golf, and show him I can play too.'
To do so, Duval will have to improve upon his past performances when paired with Woods.
This will be the third time this season Woods and Duval have been paired together over the weekend. The two first played in the final round of the GTE Byron Nelson Classic. Tiger shot 63 to tie for 4th. Duval shot 70 to tie for 20th.
The most memorable meeting between the top two Americans came in the final round of the British Open. Playing in the final group, Woods shot 69 to take home the Claret Jug. Duval shot 75 to fall into a tie for 11th.
This is also the second time in as many years the two have faced each other head-to-head at the Tour Championship. Last year, Woods and Duval played the first round together at the Champions Club in Houston, Tx. Woods fired 67 and went on to win the event. Duval carded a 70 and finished the week tied for 15th.