UNC ranked 98th in red zone efficiency defense with a 89 percent conversion rate (16/18; 11 TD, 5 FG).
The problems started early against the Blue Devils. On the game's opening drive, North Carolina drove down to the eight-yard line, only to lose five yards on its next three plays. Casey Barth converted a chip shot from 30 yards to give UNC a 3-0 lead.
Duke's ensuing ended with more success as the Blue Devils needed just two plays in the red zone – a 13-yard run by Josh Snead and a two-yard touchdown plunge by backup quarterback Anthony Boone – to take a 7-3 lead.
The Blue Devils reached the red zone on four of their first five possessions, scoring two touchdowns and adding a pair of field goals. UNC safety Tre Boston intercepted Blue Devils quarterback Sean Renfree at the seven-yard line at the 7:47 mark of the second quarter, but it accounted for the lone stop in Duke's seven red zone appearances.
North Carolina drove inside the 20 just twice in the first half, settling for short Casey Barth field goals (30, 23) each trip.
"We didn't finish anything," UNC head coach Larry Fedora said. "We'd get down in the red zone and bog down and kick a field goal… We've got to learn how to finish. How to finish a drive, how to finish a play, all of things it takes to be a good football team."
Barth added a 28-yarder after UNC stalled at Duke's 11-yard line midway through the third quarter, increasing the Tar Heels' red zone scoring to nine points on three chances.
"We've got to focus more on executing," quarterback Bryn Renner said. "On a couple of plays, we had missed assignments and bad throws by myself. We can't settle for field goals in those situations."
After scoring touchdowns in five consecutive red zone appearances beginning with the Virginia Tech win two weeks ago, North Carolina endured a stretch of one touchdown in six trips to the red zone before running back Gio Bernard's one-yard plunge in the opening minutes of the fourth quarter.
UNC's final two red zone trips resulted in touchdowns, bringing the total to a solid 5-for-5, despite field goals representing the majority of scores.
The Tar Heel defense deserves credit for limiting Duke to three field goals in the red zone, as well as the first-half turnover, but the game-winning touchdown pass from Renfree to Jamison Crowder was thrown from the five-yard line.
As it turns out, North Carolina's offense took too long to find a rhythm inside the 20 and its defense couldn't make one last play to prevent the program's first loss to Duke since 2003.