World No. 1 Rory McIlroy fired a second straight 65 on Saturday for a slim halfway lead in the Deutsche Bank Championship with Louis Oosthuizen and Tiger Woods heading the chasing pack.
Northern Ireland's McIlroy, who earned his second career major title at the PGA Championship in August, had a 12-under total of 130 after two rounds on the par-71 TPC Boston layout.
South Africa's Oosthuizen, the 2010 British Open champion, was one shot back after a 65 for 131 and 14-time major champion Woods carded a 68 for 132, where he was joined by compatriot Ryan Moore, who also carded a 68.
McIlroy's round included an eagle on the revamped par-five 18th -- his ninth hole of the day -- where he stuck his approach shot eight feet (two meters) from the pin.
He had two bogeys on his inward nine, finding the water at the par-five second for a six and also bogeying the par-three third. But he bounced back with birdies at four and five.
"Everything seemed to work pretty well out there," McIlroy said. "I felt like I drove the ball a bit better today and hit more fairways, which gave me some more opportunities to make birdies.
"And I was putting well enough to take a few of those," he added. "Yeah, pleased with where I am and looking forward to the weekend."
Overnight leader Seung-Yul Noh of South Korea had an even par 71 that included an eagle and a double-bogey and was in a group of five players on 133 that also included South Africa's 2011 Masters champion Charl Schwartzel (65).
Nine players were separated by three shots heading into Sunday's third round of the $8 million tournament, which is scheduled to end Monday on the US Labor Day holiday.
Prior to the event, the second in the US PGA Tour's four-tournament playoff series that ends with the Tour Championship in Atlanta, McIlroy predicted the winning total after four rounds on Monday would be from 15- to 18-under par.
"Now that I'm in the tournament, I just want to play as well as I can and maybe reassess things going into the last day," McIlroy said.
"But I was very happy with the two scores that I've got already and know that I need to go out and play just as good tomorrow to give myself a chance going into Monday."
While McIlroy said his putting helped him score, Woods couldn't get much going on the greens. He missed six birdie putts from within 18 feet.
"I didn't make anything today," Woods said. "There are a bunch of guys stacked up so we have to go out there and make some birdies."
Woods opened his round with birdies at the first and second holes, but he was unable to get up and down from a bunker at the par-three third and took bogey.
A birdie at the sixth was followed by a three-putt bogey at 11, but he picked up another shot at 14 where he drained a 30-foot birdie putt.
He holed a 17-footer for birdie at 17, but any hope of a birdie at the last evaporated when he found the rough off the tee and came up short with his third shot.
Oosthuizen also teed off on 10 and his round included five birdies and a chip-in for eagle on the par-four fourth, with just one bogey.