By Mark Lamport-Stokes
ATLANTA (Reuters) - FedExCup points leader Chris Kirk maintained control of the season-long race for playoff honours as he surged into a share of the lead in Thursday's opening round of the elite Tour Championship.
Kirk, who took over at the top of the standings with his victory at the Deutsche Bank Championship earlier this month, fired a four-under-par 66 to set the pace with fellow American Billy Horschel in the PGA Tour's season-ending event.
Northern Irish world number one Rory McIlroy, hunting his fourth PGA Tour victory of the year, returned a 69 to remain in contention for overall playoff honors, a title he has never previously won and has specifically targeted this week.
As the leading two players in the FedExCup standings, Kirk and Horschel were drawn together for the opening round and they clearly benefited from what Kirk called a comfortable pairing.
"We both had a solid day," Kirk told reporters after emulating his playing partner by recording four birdies in a bogey-free display on a sunny but muggy afternoon.
"Billy's obviously been playing some pretty incredible golf with winning last week and finishing second the week before, and I've been doing all right myself.
"So it was a comfortable pairing for both of us, and the golf course played really, really well. It was tough, but very fair. And we both had it going pretty nice."
Kirk picked up shots at the first, eighth, 15th and 17th, where he chipped in from off the green, to remain in pole position for FedExCup honors and the $10 million bonus.
"I felt comfortable with my play and judged the ball pretty well," said the 29-year-old, who has won twice on the 2013-14 PGA Tour.
"Made what I needed to. Made a few putts when I needed to. Chip-in on 17 was a nice bonus to cap off my round there, but all in all pretty solid game."
In-form Horschel, rose to second in the FedExCup points list by winning the BMW Championship on Sunday, birdied the par-five ninth before picking up three more shots after the turn.
"Chris and I both played a beautiful round of golf out there today," said Horschel, a double winner on the PGA Tour. "I don't believe we had a bogey between us.
"(Combined) eight under par, no bogeys, great round. Especially on this golf course, the way it's set up. Chris and I get along very well. We seem to always play well when we're paired together."
Masters champion Bubba Watson also got to four under, having rebounded from a double at the 13th with three successive birdies, but he bogeyed the par-three last to open with a 67.
"Silly bogey on 18," said left-hander Watson, who piled up seven birdies in his round. "But other than that, a good day, a good start. I'm looking forward to the next three days."
Also at three under in the PGA Tour's fourth and final playoff event were Australian Jason Day, whose caddie had to withdraw after seven holes because of a back problem, and Americans Patrick Reed and Jim Furyk.
McIlroy, who has enjoyed a brilliant 2014 campaign, clinching two major titles among four wins worldwide, was a little frustrated after a 69 that included four birdies and three bogeys.
"Hopefully I can show a little bit more consistency over the next few days," said the 25-year-old Northern Irishman. "Finish it off the way I feel I should finish it off.
"It's been a great season. Even though I haven't played my best in these FedExCup playoffs ... I definitely want to win here and win the overall thing."
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), Watson (third), McIlroy (fourth) and Hunter Mahan (fifth).
Due to the threat of thunderstorms forecast for Friday afternoon, tee times for the second round have been brought forward by three hours.
(Editing by Frank Pingue)