Lahiri's 75 placed him 110th and in danger of missing the cut. Though he was 61st starting the week and should stay on for the next event, too.
Lahiri is the first Indian to figure in the FedExCup play-offs. He qualified last year but skipped it.
The leader was Russell Henley, who found his form at the right time with a 64 after a series of not-so-good results.
Lahiri started with a bogey-double to be three-over in two holes. His only birdie came on the third, when he putted from eight feet and then he missed a bunch of putts under 10 feet and had bogeys on eighth and ninth to turn in four-over 59.
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On the back nine, he eagled 13th with a hole out from the intermediate and then bogeyed 14th, 15th and 17th. He ended with 75 and would need a solid second round to make the cut.
The top-100 in the FedExCup after this week advance to the second Playoff event at the TPC Boston.
Dustin Johnson, who took a week off and went to Bahamas and switched back to his old putter, had three birdies over his last six holes and finished with a 5-under 65 to trail Russell Henley by one shot. Johnson missed only two fairways and two greens.
Scott Brown, Camilo Villegas and Chris Kirk were at 66, and it was an important start for Villegas and Kirk.
It was even better for a few players who opened with a 67, such as Bubba Watson (No. 113), Martin Flores (No. 118) and Harold Varner III (No. 123). Flores only got into the top 125 by finishing with an ace, a par and a birdie last week at the Wyndham Championship.
Phil Mickelson, meanwhile, needs to see a score much better than his 72, which featured two straight birdies at the end but also a pair of double bogeys.
Mickelson has played in every Presidents Cup or Ryder Cup since 1994, and he is in danger of being left out of The Presidents Cup next month at Liberty National.
Open champion Jordan Spieth had a 69, while Hideki Matsuyama, the No. 1 player going into the Playoffs, didn't make a birdie and opened with a 74.
Rory McIlroy made three bogeys on the back nine and shot 73.