Lahiri had a fine start with a 68 in the first round, his ninth score of 70 or below in 10 starts this season.
However, he had a bogey-bogey start in the second round and then Lahiri struggled all the way to the 16th tee, at which point he was six-over for the day and three-over for the tournament, and was certain to miss the weekend.
The cut was expected to fall at even but Lahiri produced three birdies in succession to squeeze inside the cutline.
Lahiri bogeyed the first two holes, birdied the third and again bogeyed fourth. A bogey on seventh meant he turned in three-over 39 and he was even for the tournament. A double on 10th and a bogey on 15th meant he was almost out before the three birdies hauled him back.
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Bud Cauley (66) went out in the morning and got to 8- under but later in the afternoon Tony Finau (65) produced a great round to get into a share of the lead as the weekend approached.
Earlier he holed a wedge shot from 105 yards for an eagle on 11th.
Cauley is yet to win after six seasons as a pro, while Finau won the Puerto Rico Open last year.
The 23-year-old Australian Cameron Smith (65), Kevin Chappell (68), Robby Shelton (69) and veteran 1994 Texas Open winner Bob Estes (69) are all in tied-third at seven-under.
Ian Poulter, Europe's Ryder Cup star, missed the cut and lost his fully exempt status on the PGA TOUR.
Apart from Poulter, also missing the cut were US amateur champ Curtis Luck (73-72) in his pro debut, Billy Horschel (73-74), Luke Donald (76-72), Zach Johnson (74-74) and Keegan Bradley (77-74).