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Longtime North Carolina assistant coach Andrew Calder knows it will take time for his young team to take shape.

The 12th-ranked Tar Heels struggled early against No. 4 Tennessee's defense to fall behind big and never recovered in an 81-65 loss Monday night, a teaching moment for a team featuring the nation's top-ranked recruiting class.

"We're going to continue to work," Calder said. "We're going to continue to get better. ... In the end, it's my responsibility to make sure they take good shots and I get them good shots. We had to take some forced shots tonight. We were not getting into our offense as much as we wanted to. Again, that responsibility is on me."

Calder — who is leading the Tar Heels while Hall of Fame coach Sylvia Hatchell is being treated for leukemia — saw his team shoot just 24 percent in the first half to fall behind by double figures. They committed 23 turnovers.

Top freshman Diamond DeShields struggled in her second college game, scoring eight points on 3-for-15 shooting before fouling out with 2:10 left. Only one UNC player — junior Brittany Rountree, who had 13 points — hit at least half her shots.

"They've just got to get used to the tempo and atmosphere," Tennessee coach Holly Warlick said. "They're going to be fine. They are a great basketball team, very talented, very athletic, and they'll figure it out."

Ariel Massengale scored a career-high 20 points while Isabelle Harrison added 14 for the Lady Vols (2-0), who led by 12 points at halftime then scored the first seven points of the second half to blow the game open.

Tennessee shot 40 percent but knocked down eight 3-pointers, while its defense harassed the Tar Heels (1-1).

Freshman Allisha Gray had 15 points and 10 rebounds to lead UNC, which shot 30 percent (21 for 69).

Hatchell, who was released from the hospital last week, addressed the team during their pregame meal and Calder led the team from the sideline.

Massengale, a 5-foot-7 junior, finished 5 of 12 from the field with all of her baskets coming from 3-point range. She matched her career-high with six rebounds to go with seven assists and three steals in 40 minutes. Harrison went 4 of 5, including a key jumper at the 5-minute mark after the Tar Heels had cut a 21-point lead down to 11.

The Tar Heels beat Air Force 87-26 in Friday night's opener, with DeShields and fellow freshman Stephanie Mavunga saying afterward that they were focused on taking advantage of those 40 minutes to get ready for the Lady Vols.

But the Lady Vols' physical defense locked down on the Tar Heels early, frustrating the youngsters to the point that UNC's offense began devolving into a lot of 1-on-1 play. At one point, Calder wandered out onto the court during a stoppage and screamed at his team to "Run the offense!"

Mavunga finished with 11 points and 12 rebounds, while sophomore Xylina McDaniel had 12 points and 10 rebounds.