Renfree led the Blue Devils into the red zone in the final minute, and after Jela Duncan's 2-yard run on third-and-4, Duke called its final timeout with 19 seconds left. Renfree then rolled and found a leaping Crowder over the middle for the go-ahead score.
Duke snuffed out a series of laterals on the Tar Heels' final play, and the students poured onto the Wallace Wade Stadium field to celebrate the Blue Devils' first win against North Carolina since 2003 and their first home victory in the series since 1998.
Backup quarterback Anthony Boone and Duncan each had 2-yard scoring runs and Ross Martin kicked four field goals for the Blue Devils, who have their best record through eight games since the 1994 team opened 7-1 on its way to the Hall of Fame Bowl - the school's most recent postseason appearance.
Bernard had 143 yards and two touchdowns - including the bizarre one with 3:12 left that gave North Carolina a short-lived lead.
Bryn Renner hit a wide-open Erik Highsmith over the middle for 36 yards to the Duke 24. Jordon Byas knocked the ball loose and when it slipped away from Duke teammate Ross Cockrell, Bernard gleefully scooped it up and took it in from 4 yards out to make it 30-26 and send the UNC bench into delirium.
Renner finished 19 of 32 for 198 yards - he was 9 of 13 for 162 in the fourth quarter - for North Carolina. An offense that entered averaging 40 points and 486 total yards managed only three Casey Barth field goals through three quarters before reeling off three touchdowns in the fourth.
Its defense was gashed by Duke's previously nondescript rushing attack, with the Blue Devils rolling up 510 total yards and 234 yards rushing - the most ever on the ground by a David Cutcliffe-coached Duke team, and the most allowed this season by a North Carolina defense that entered ranked in the ACC's top tier in every significant stat category.
Three rushers had at least 64 yards apiece for Duke, with Josh Snead leading the way with a career-high 99.