FedEx Cup points leader Chris Kirk maintained control of the season-long race for playoff honours as he surged into a share of the lead in the 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 honours, 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."
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 honours and the $10 million bonus.