Tiger Woods moved into a narrow Tour Championship lead at East Lake Golf Club at the halfway stage of the PGA Tour&aposs FedEx Cup finale. The world No.1, a six-time winner already this year, shot a second-round, two-under-par 68 to get to five-under-par for the tournament – a shot ahead of Ireland&aposs Padraig Harrington and fellow American Sean O&aposHair on a sweltering day in Atlanta, Georgia. Australian John Senden is five shots adrift of Woods on even par after he carded his second consecutive round of 70. Yet Woods could well have finished the day in an even more dominant position after a couple of missed short putts at the 15th and 16th holes and a closing bogey at the par-three 18th. O&aposHair had begun the day at four-under-par, a one-shot leader over Woods, Harrington and Stewart Cink with a fellow major winner, reigning US Open champion Lucas Glover, a further shot back at two-under in fifth place. But as the frontrunners reached the turn, Woods sank his third birdie in a row with a four at the 9th to move clear by one shot at the top of the leaderboard. Woods was playing with Ireland&aposs Harrington in the penultimate group ahead of Open champion Cink and O&aposHair. It was their eighth round together this year, and Harrington had struck first blood in this duel with a birdie at the par-four 4th to move into a share of the lead at four-under. The gap widened as Woods then three-putted the par-four 5th for bogey and slipped to two-under-par but parity was restored at the par-four 7th when the Irishman overshot the green on the way to a bogey while Woods nailed his approach shot to seven feet from the hole and birdied from there. Both Woods and world No.8 Harrington birdied the par-four 8th while behind them Cink birdied the 7th as O&aposHair bogeyed the same hole and briefly the three chasers had swapped places with the overnight leader. Then, at the par-five 9th, as Harrington could only take par from the easiest hole on the course, Woods sunk a mid-range birdie putt to move into the outright lead at five-under. Harrington joined him there with a birdie at the 12th but then gave the shot back two holes later. Woods looked to have separated himself from the rest of the 30-man field at the par-five 15th with a brilliant five-wood from 246 yards out to five feet from the hole, only to miss the eagle putt. Still, the birdie went in and he moved to six-under, two shots clear. A five-foot birdie putt at the 16th gave Woods another chance to put more daylight between him and Harrington but again, he missed from short range and next the Irishman wasted an opportunity of his own, missing a birdie putt from inside six feet at the 17th. Woods, though, paid for poor play at the par-three 18th, sending his tee shot into a greenside grandstand and then, having taken relief, fluffing his chip shot out of the rough. He got out of the thick stuff at the second attempt and holed out for bogey, falling back to five-under. O&aposHair had gone off the boil with a bogey either side of the turn but he rallied and had the chance to leapfrog Harrington into second place but missed a birdie putt at the 18th from 17 feet. Instead, Harrington will once again go toe-to-toe with Woods on Saturday, this time in the final group, with O&aposHair a group in front alongside South African Ernie Els, who got into the mix at three-under with a 66. Americans Kenny Perry and Jerry Kelly will start the third round in a tie for fifth at two-under with a group of five players at one under, including Masters champion Angel Cabrera, Glover and Cink, whose round came unstuck with a quadruple bogey eight at the 10th on the way to a 72. Among those at level par with Senden is world No.3 Phil Mickelson, who made amends for an opening 73 with a six-birdie, three-bogey 67. A victory for Woods, as FedEx Cup points leader, would guarantee the world No.1 a $US 10 million ($AU 11.5 million) bonus in addition to the $US 1.35m ($AU 1.5m) winner&aposs cheque. Harrington, sixth in the standings, would need to win and have Woods finish third or lower. Of the four men between Woods and three-time major winner Harrington, all of whom need to win to guarantee them the FedEx Cup title and bonus, third-placed Jim Furyk was best placed, four shots back at level par after a 68. Fifth-placed Heath Slocum shot a 68 to reach one-over-par while second-placed Steve Stricker and fourth-placed Zach Johnson are at two-over after 72s. England&aposs Luke Donald, the only other European at East Lake besides Harrington, fired a 71 and is at one over, while Senden&aposs compatriot Geoff Ogilvy props up the 30-man field at eight-over following a second-round 73. US Tour Championship second round -5: Tiger Woods 67 68 -4: Padraig Harrington 67 69, Sean O&aposHair 66 70 -3: Ernie Els 71 66 -2: Kenny Perry 72 66, Jerry Kelly 71 67 -1: Angel Cabrera 72 67, Jason Dufner 71 68, Nick Watney 70 69, Lucas Glover 68 71, Stewart Cink 67 72 E: David Toms 74 66, Phil Mickelson 73 67, Jim Furyk 72 68, John Senden (Australia) 70 70, Steve Marino 69 71 +1: Heath Slocum 73 68, Scott Verplank 70 71, Luke Donald 70 71, Retief Goosen 69 72 Also: +4: Marc Leishman (Australia) 70 74 +8: Geoff Ogilvy (Australia) 75 73