Northside point guard Jenay Wilson had three steals and six points in the final quarter as the Lady Eagles solved the Lady Wolfpack's full-court press.
No. 2 Greenbrier had used the full-court press to shave five points from an 11-point deficit with more than six minutes still left in the game.
"We were struggling," said Wilson, who finished with 12 points. "I couldn't watch anymore."
She entered the game with Greenbrier trailing 52-46 with the ball
The Lady Wolfpack misfired on that possession, then after a Northside miss on the other end, the senior came up with a steal that led to a bucket by freshman Tai Brown, who paced the Lady Eagles with 16 points.
Brown's bucket started a spurt in which Northside outscored the Wolfpack 13-7 over the next three minutes. Wilson had each of her steals and all of her points in the surge.
"We had those two chances to get it to a four-point game but let it slip away," Greenbrier head coach Garrett Black said. "We missed a shot, then had that turnover they scored on. Once (the lead) got back around 10, we couldn't get it back because of their athleticism."
Northside won despite 30 turnovers and connecting on just 14 of 33 free throws. Northside took the lead for good with a run of 11 consecutive points spanning the first and second quarters.
Greenbrier led 11-10 after Michelle Swiec, who led the Lady Wolfpack with 18 points, hit a layup with 1:44 left in the first quarter. The Eagles then shot into the lead with the spree that ended on consecutive layups from Josey Tolliver, who scored 11 points.
The run handed Northside a 21-11 cushion with 5:44 left in the half, and Greenbrier never got closer than the six-point deficit in the last period.