Matsuyama hit six birdies and a bogey, while Hearn sunk four birdies, a bogey and an eagle on the par-five 11th. Hoffman finished with eight birdies and a triple bogey on the par-four 1st, while Na got six birdies and a bogey.
Sitting one stroke behind them is Troy Merritt, Ben Martin, Billy Horschel, Brendon Todd, Charles Howell III and Derek Fathauer.
Merritt hit six birdies and two bogeys, Martin registered five birdies, including three in a row from the 11th to 13th, and a bogey, while Horschel ended up with the same.
Todd got two birdies and an eagle on the par-five 16th, Howell recorded four birdies and Fathauer turbulent round consisted of four birdies, four bogeys and two eagles, which came on the par-five 2nd and par-four 4th.
World number one Rory McIlroy remains two strokes behind the leaders after he hit a first round 69, which included two birdies, a bogey and an eagle on the 16th.
Meanwhile, Tiger Woods had a rough first round as he hit five birdies, two bogeys and two double bogeys during his 73.