The weekly playoff format means Lowry is now under pressure in today's round.
Shane Lowry is 1 over par following the opening round of the FedExCup playoffs.
The Open Champion had a mixed bag of five bogeys and four birdies in signing for a round of 72.
Rory McIlroy however will go into the second round of the Northern Trust five shots off the lead.
The world number 3 carded a 2-under par round of 69 in Boston yesterday.
Harris English, Kevin Streelman and Cameron Davis head the field on 7-under par.
The other Irishman in the field, Graeme McDowell is 6 over.
McIlroy doesn't feel at the peak of his powers right now.
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