Garcia opened with five birdies in seven holes, and then knocked in an 18-foot eagle putt on the 18th hole at the TPC Boston for a 7-under 64 and a one-shot lead over Roberto Castro among the early starters in the second round.
Matt Kuchar had a 66 and was three shots behind.
Phil Mickelson, who opened with a 63, was among the late players on a cloudy afternoon and playing for the second straight day with Tiger Woods, who was 10 shots out of the lead when he teed off.
Garcia is not a regular at the second FedEx Cup playoff event. He prefers to take this week off to rest, but he couldn't guarantee that he would be among the top 70 in the standings after the Deutsche Bank Championship who advance to the third event
So far, it looks like a good move.
"Unfortunately, I didn't play well enough and it was touch-and-go if I was going to make the BMW without playing here," said Garcia, who is at No. 55. "Sixteen guys could easily pass me if they played well. So we decided to come here and make a little bit of an extra effort of playing five weeks in a row, which I don't usually enjoy very much."
Garcia looked as if he would be much higher in the FedEx Cup standings earlier this year, when he had top 10s in a World Golf Championship, the Masters and The Players Championship. But his year took a bad turn off the course. During a two-week spat with Woods that began at The Players Championship, Garcia jokingly said during a Q-and-A at an awards dinner in London that he would invite Woods over during for dinner during the U.S. Open and serve fried chicken.
He apologized the next day, though he was clearly rattled. Garcia hasn't finished in the top 20 since.
"Everything has been kind of a little difficult, but it's good," Garcia said. "It's been a good learning experience. So I think that you always have to try to take the positives out of all those things and learn from your mistakes. And hopefully, (they) make you a better player, a better person."
For the longest time, the morning portion of the second round was a duel between Garcia and Castro.
Castro made an eagle on the par-5 second hole and made the turn in 7-under 29. But he didn't give himself good birdie looks the next three holes, missed the green long on No. 13 for bogey and then took two shots to get out of a grassy mound short of the 14th hole and took double bogey. He birdied two of the last three for a 65.
For some players, their season ended Saturday.
William McGirt, Luke Guthrie, Greg Chalmers and Scott Brown were among those who were out of the top 70 and appeared headed toward a missed cut. Kyle Stanley was at No. 66 and missed the cut, meaning his season was likely over.
Ernie Els and Ian Poulter are still in the mix.
Els is at No. 91, but he found something in his game this week and was at 7-under 135. He would need to be about 15th or better to advance.
"It's a nice little challenge I've got," Els said.
Poulter is at No. 77 and doesn't have a great record on the TPC Boston. But he feels he is playing well, and is angry at the thought that if he doesn't advance to the BMW Championship, he has the next seven weeks at home.
"I'm playing well and I don't want the time off," Poulter said after a 68 put him at 8-under 134.
Rory McIlroy is safe for the third playoff event. He just wanted two more days in Boston. McIlroy was safe inside the cut until taking a double bogey on the par-5 18th by hitting 4-iron into the hazard and wedge over the green from the drop zone. That gave him a 71 for 1-under 141, and he had to wait the rest of the day to see if it was enough.