Garcia is 19-under following a 65 that allowed him to stay atop the leaderboard. He was pushed by Henrik Stenson until the Swede three-putted for bogey on 17 and settled for a 66 that leaves him alone in second.
Graham DeLaet and Steve Stricker are three strokes back and one ahead of PGA champion Jason Dufner and Robert Castro.
Phil Mickelson and Tiger Woods are out of contention. Mickelson is 12 strokes off the pace and one ahead of Woods.
Source: Associated PressSergio leads Deutsche Bank Open by Matt Serio