Maybe it was finally getting resolution in the P.J. Hairston saga. Maybe it was a key lineup switch Roy Williams made early in league play. Maybe it was simply a matter of learning the importance of playing hard regardless of the opponent.

Whatever the reason, a North Carolina team known best for its schizophrenic tendencies through mid-January has suddenly curbed its erratic ways, forged a defense-first identity and reinvented itself as a model of consistency.

Already riding a seven-game win streak entering Thursday night's showdown with Duke in Chapel Hill, the Tar Heels extended that run to eight with a come-from-behind 74-66 win over the fifth-ranked Blue Devils. Duke led by as many as many as 11 points early in the second half before North Carolina launched a comeback fueled by stifling defense and some key late baskets from point guard Marcus Paige.

Thursday's victory moves North Carolina within a half game of Duke for third place in the ACC and makes the Tar Heels the first team in the 53-year history of the AP poll to beat the preseason No. 1, 2, 3 and 4 teams in the same season. It was tough to know what to make of those early-season wins over Louisville, Michigan State and Kentucky because they were preceded by losses to Belmont, UAB and Texas, but the team that beat Duke on Thursday night feels far more reliable.

No longer concerned about whether they'll have Hairston or Leslie McDonald available, the Tar Heels have been able to establish an identity over the past six weeks. They don't shoot well from the perimeter or the free throw line with the exception of Paige, but they make up for it by defending the rim, crashing the offensive boards and turning turnovers into transition baskets.

Marcus Paige has thrived in the role of go-to perimeter scorer all season and has been even better since Roy Williams took Nate Britt out of the starting lineup last month and put the ball in Paige's hands as a point guard. James Michael McAdoo has become more efficient scoring in the paint during North Carolina's win streak, aside from his no-show against Florida State earlier this week. And while the rest of the Tar Heels haven't been consistent, enough role players have stepped up in spurts that North Carolina has scored more than 1.1 points per possession during its recent hot stretch.

It was defense that began North Carolina's turnaround Wednesday night.

Roy Williams mixed in more zone after Duke built its lead to 11, contributing to the Blue Devils going nine minutes between field goals. Duke missed five 3-pointers during that stretch but also struggled to finish at the rim against the rangy North Carolina frontline.

North Carolina's comeback was more a methodical climb than a sprint because its own offense stalled at times, but Paige ignited the Tar Heels late in the second half.

Held scoreless in the first half and to only four points in the first 34 minutes, Paige caught fire down the stretch as Williams ran more ball screens for him to create space for him off the dribble. All 13 of his points came in the second half including a critical 3-pointer that trimmed Duke's lead to one with 5:31 to play and back-to-back baskets in the final two minutes that extended North Carolina's cushion to four.

Duke stayed in front of North Carolina for a while thanks to strong first halves from Jabari Parker and Rodney Hood and an improved performance from Quinn Cook, but the Blue Devils were 5 of 22 from behind the arc. Given the way North Carolina clogged the lane, Duke couldn't survive that off night from the perimeter.

Thus North Carolina beat another highly ranked team, its fourth victory of the season over a team touted as a national title contender.

It was hard to know what to make of the first three wins because of North Carolina's maddening inconsistency. The team that celebrated amid a sea of Tar Heels fans Thursday night feels far more trustworthy.