UNC dominated the first 20 minutes of play, with Matt Crawford scoring two goals in 10 minutes.
Despite being outplayed by Long Island for most of the game, UNC walked off the field with the 4-2 victory, clinching its 15th straight win at Fetzer Field.
UNC's first goal came after Ryan Kneipper flicked the ball over the Blackbird defense. As Long Island goalkeeper Ryszard Gorski came 25 yards off his line to challenge, Crawford coolly slid the ball past him to give North Carolina (3-0) an early 1-0 lead.
Kneipper, who scored three times in UNC's first two games, was largely ineffective after assisting on the first goal.
"I think what they really tried to do was get him out of his game physically and foul him a lot," said UNC midfielder Marcus Storey.
By fouling Kneipper, and catching the Tar Heels offside seven times in the first half, Long Island (1-1) severely disrupted UNC's attack.
But, in the 20th minute, UNC struck again.
Long Island's Bereket Kidane took down UNC's Mike Gell well behind the play, but the official did not see it. Gell got up to have words with Kidane, and Kidane hit him in the throat. But Gell played on.
David Testo sent a long ball from the far flank into the box. Gell headed it off the ground and back to Crawford who headed it home for his second goal.