Jason Day’s back hurts, Phil Mickelson and Bubba Watson off to sizzling starts at The Barclays

Bird(ie) is the word for Phil Mickelson and Bubba Watson early at The Barclays, as both guys kicked off their 2015 FedEx Cup playoff runs with a bunch of low numbers in Thursday’s opening round.

Meanwhile, Jason Day’s first start since winning the PGA Championship two weeks ago could be a short one if his balky back keeps acting up.

Day, who withdrew from Wednesday’s pro-am at Plainfield after tweaking his back, grabbed at the injured area in apparent discomfort following a tee shot on the par-4 12th hole.

Day two-putted for a birdie on 12, his second of the opening round that he, Jordan Spieth and Bubba started on No. 10, and appeared to show no further signs of pain until the 16th.

A bogey at the par-5 16th left Day sitting three shots back of co-leaders Mickelson and Watson and perhaps wondering if he should continue playing at all.

Lefty made par on his first hole (also the 10th) and then went birdie-birdie-birdie-par-birdie-par-par-par to finish off his outgoing nine.

Mickelson, who likely needs a stellar week to punch his ticket to South Korea in October, made the turn at 4-under.

Bubba, for his part, got off to a birdie-birdie start and added another pair on 13 and 15.

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