Four putts later, he was 2 over and walking in stunned silence to the back nine.
Mickelson hit a textbook drive 311 yards to the middle of the fairway on the par-4, 472-yard dogleg left. His second shot was in the center of the green, with a long putt back toward the pin in the front right.
Mickelson, who won the tournament in 2007, was wide of the hole but only needed to sink the 3 1/2 -footer to save par. He put that one about five feet past the hole and then, after picking up his ball and catching his breath, slid his third put past the lip.
He tapped in from 6 inches for a double-bogey 6.
EASY EAGLES: One of the most forgiving holes on the TPC Boston course on Friday was No. 4, a 298-yard par 4 that gave up seven eagles and 48 birdies to the 99 players. With a scoring average of 3.48, it was the second-easiest on the day.
But the players were awakened when they got to the next hole, a 466-yard, par 4 that was the toughest, with a scoring average of 4.182.
The easiest was No. 18, a 528-yard par 5 that gave up three eagles and 55 birdies but only four bogeys and two double bogeys.
DIVOTS: Troy Matteson, who earned the 125th and final spot in The Barclays and used a top-20 finish to reach the second round of the playoffs, opened with a 5-under 66 and was tied for eighth. If he stays where he is, he would qualify for Week 3 at the BMW Championship. … It was Mickelson’s 400th career PGA Tour start. … It’s the second time this year Furyk has been atop the leaderboard after the first round. The other time was in Tampa, where he followed a 65 with a 78. … Defending champion Vijay Singh, who also won in 2004 and finished second in ’06, shot 67.