Lahiri hit five birdies against two bogeys at the end of 18 holes.
Daniel Chopra, playing only his second PGA Tour event this season, shot three-over 74 and will need a very low number to make the cut.
Meanwhile, the leader was Australian Marc Leishman, who has one of the best scoring averages in tournament history as he opened with a 10-under 61 round.
J J Spaun and Texan Jimmy Walker were three shots back at seven-under 64.
Spaun had six birdies in a span of seven holes for a 30 on his second nine. Local star Jordan Spieth was eight shots behind the leader with a round of two-under 69.
Lahiri birdied fifth and seventh, but a dropped shot on ninth meant he turned in one-under. A second bogey on 10th brought him back to even par, but birdies on 11th, 14th and 16th meant he finished at three-under.
The 34-year-old Leishman opened with an eagle, started the back nine with three straight birdies and reached nine-under with another eagle at the 14th.
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