ATLANTA (Reuters) - Billy Horschel, seeking a second consecutive PGA Tour victory, birdied three of the last eight holes to move two strokes clear of the chasing pack in the Tour Championship second round on Friday.
The American, ranked second in the FedExCup standings coming into this week, fired a second successive four-under-par 66 at East Lake Golf Club to seize control of the fourth and final playoff event with an eight-under total of 132.
However, Northern Irish world number one Rory McIlroy was in hot pursuit after carding a best-of-the-day 65 in hot and humid conditions to soar into a three-way tie for second at six under.
McIlroy has already enjoyed a brilliant 2014 campaign, clinching two major titles among four wins worldwide, and has now set his sights on claiming playoff honors on the U.S. circuit for the first time after a season-long race.
"I just want to finish my season off the way I feel like I should and the way I feel like it deserves to be finished off," McIlroy told reporters after piling up six birdies and a sole bogey with a sizzling display in the second round.
"I'm not putting too much pressure on myself because it's already been a great year, but I still want to win this thing."
Level with McIlroy at six under were Australian Jason Day (67) and American Chris Kirk (68), the FedExCup points leader who had been joint pacesetter with Horschel after the opening round.
Horschel, who tied for second at the Deutsche Bank Championship two weeks ago and then won the BMW Championship on Sunday, did well to par the short 18th after hitting his tee shot into a greenside bunker and splashing out to seven feet.
He coolly sank the par putt to end his day with an overall tally of six birdies and two bogeys, in pole position heading into the weekend with his sights set on victory and the staggering FedExCup playoff bonus of $10 million.
"Drove the ball really well today," said the 27-year-old Horschel, arguably the hottest player in the game. "Just didn't hit very good chips, but played pretty solid coming in. Probably could have hit some better iron shots.
"But I'm happy with the way I played today. I'll take two more 66s, see where that puts me on Sunday."
Horschel, McIlroy, Kirk, Day and American Patrick Reed all held at least a share of the lead in the second round as the players jostled for position in the PGA Tour's season-ending event.
Kirk, who won the second playoff event earlier this month, slipped back with two bogeys in the first six holes but rebounded in style as he drained successive birdie putts from 26 feet at the seventh and eighth.
He picked up another shot at the par-five ninth, where he sank an eight-footer, to join Day in a tie for the lead at six under, then knocked in a six-foot birdie putt at the 10th to edge a stroke in front.
However Kirk stumbled with a three-putt bogey at the short 11th to drop back into a three-way tie at the top with Day and Horschel, who moments earlier had rolled in a 13-foot birdie putt on the 11th green.
Day and Horschel both birdied the 14th to get to seven under, Horschel by draining a 25-footer, but the Australian faltered with a bogey at the last after missing the green to the right off the tee.
McIlroy had ended his round with a birdie-birdie flourish for a brief share of the lead but Horschel moved two strokes clear at the top after hitting a superb approach to four feet at the 17th and knocking in the birdie putt.
Any of the top five in the points standings would clinch the FedExCup by winning the Tour Championship - and that quintet comprises top-ranked Kirk, Horschel (second), Bubba Watson (third), McIlroy (fourth) and Hunter Mahan (fifth).
Tee times for the second round were brought forward by three hours due to the threat of thunderstorms forecast for Friday afternoon.
Editing by Gene Cherry/Frank Pingue