CANCUN, Mexico (AP) -- Pittsburgh shadowed Duke's shooters on the perimeter, so the Blue Devils did the only thing they could.
They drove to the basket and got plenty of trips to the free-throw line.
In a matchup of undefeated teams, Lindsey Harding scored 22 points and No. 4 Duke made 30-of-36 shots from the line for a 72-51 victory Thursday over No. 22 Pittsburgh in the final game of the Caribbean Classic Tournament.
Carrem Gay added 12 points, Wanisha Smith had 11 and Abby Waner scored 10 for the Blue Devils (12-0).
"We wanted to be aggressive; Wanisha did a good job," said Duke coach Gail Goestenkors. "They were pressing us on the perimeter, so we needed to get to the basket."
Marcedes Walker led Pittsburgh (12-1) with 15 points, and Xenia Stewart added 10.
The Blue Devils pulled away in the opening minutes with a 9-0 run, fueled by an aggressive press, to take a 13-4 lead after five minutes.
"I'm proud of the team on the defensive end," Goestenkors said. "Offensively, there's still room to grow."
With shot-blocker Alison Bales in early foul trouble, the Blue Devils picked up their defense on the perimeter, disrupting Pittsburgh's offensive flow. Pitt's Shavonte Zellous, one of the country's leading scorers at 20.9 points per game entering the match, had just eight points.
It was Duke's fifth win over a ranked opponent in its last six games.
"We've had a tough schedule; it was a very good challenge," Goestenkors said. "We passed our final exams."
Duke led 36-27 at halftime, thanks to 10 points by Harding and eight points from Gay. The Blue Devils sank 12-of-17 free throws in the opening half and shot 42 percent from the floor.
Duke opened the second half with a 11-4 run for a 47-31 lead. Pittsburgh trimmed the lead to 10 after Zellous' layup made it 53-43 with 12:18 remaining. But Duke followed with an 11-0 spurt to open a 64-43 gap with seven minutes remaining. The Panthers never recovered, finishing 18-of-52 for 35 percent from the field and making just 1-of-8 from beyond the arc.
"It's nice going to Christmas [break] undefeated, but we still have a long way to go," Waner said.