"Playing good any time of the year is always fun," he said. "But obviously now, where I kind of have to get into the next event up the road, I know that unless I play well, I'm going home. And I don't want to go home. No offense to my wife or kids or anything, but when you're playing well, you want to stay on the road."
Phil Mickelson had a 70 and was at 137.
"I would have liked to have been more under par because when K.J. gets it going, he's got the ability to keep going, so he's going to be tough to catch," Mickelson said. "But a good round tomorrow, maybe I'll have a chance on Sunday."
Woods, who chose to sit out this event, could wind up 6,500 points behind if Choi were to win.
Even now, Choi finds it hard to believe what he has done this year, especially his victories against strong fields on strong courses, such as the Memorial in early June and a month later at Congressional in the new AT&T National.
He attributes his turnaround to his driving. Instead of trying to shape a tee shot depending on the hole, Choi worked with coach Steve Bann on a consistent fade that he seems to have perfected. He has missed only two fairways in each of the first two rounds at The Barclays, allowing him to take advantage of mild conditions.
"I found myself constantly changing my shots, and there was no consistency," Choi said. "But this year, I just learned to play one shot, a fade shot. Just hit it in one direction, whether it's a dogleg left or whether it's a dogleg right. It's made a lot of difference."
Choi and Sabbatini were tied after playing the back nine, but the South Korean quickly pulled away.
He chipped it from about 15 yards short of the par-3 first hole, hit a 7-iron to about 4 feet on the third hole for birdie, then seized command of the tournament with his sand wedge that hopped into the hole.
"I hit a high ball and couldn't see," Choi said. "Everybody started jumping up and down."
Beem has struggled to put good rounds together, and it appeared this might be another slide when he chopped up the second hole, first going into the bunker and then three-putting from 8 feet for double bogey. But he birdied three of the next four holes and managed a 68 despite failing to birdie two of the par 5s.