DURHAM, N.C. -- With a tougher part of the schedule arriving for Duke, coach Mike Krzyzewski said the Blue Devils' toughness could make the biggest difference.

That was one of the conclusions after Duke's 72-65 victory against No. 13 Louisville on Monday night at Cameron Indoor Stadium.

"It's just how they've grown," Krzyzewski said of his team, which has won four of its past five games. "You can't diagram toughness. (Our players) keep getting better and keep getting tougher."

Guard Grayson Allen scored 19 points, and Duke used key late-game free-throw shooting to ruin Louisville's first visit to the historic venue.

The Cardinals took a brief lead down the stretch before Duke recovered. The Blue Devils made 10 of 12 free throws in the final 3:14.

"All the momentum went to them," Krzyzewski said. "You could look at our guys and they were tired. We showed amazing grit. By the end of the game, we were just fighting."

Forward Brandon Ingram scored 18 points, guard Luke Kennard added 11 points and center Marshall Plumlee had 10 points for Duke (18-6, 7-4 Atlantic Coast Conference). The Blue Devils are unranked for the second week in a row as they start a brutal portion of their schedule that includes four consecutive ranked opponents.

"Two weeks ago, we wouldn't have won this game," Allen said, pointing to Duke's maturation. "We would have been blown out."

Guard Donovan Mitchell's 17 points paced Louisville, which trailed by 15 points early in the second half. Guard Quentin Snider had 12 points, guard Trey Lewis added 11 points and guard Damion Lee scored 10 points for the Cardinals (19-5, 8-3).

"It was a great atmosphere," Louisville coach Rick Pitino said. "My first time here. I really enjoyed it, except for the game."

The Cardinals dropped out of a first-place tie in the ACC with North Carolina.

The Duke lead was at 44-30 after guard Matt Jones' 3-pointer early in the second half. He had a scoreless first half.

A flagrant foul on Allen for tripping with 13:55 remaining helped Louisville close the gap to 44-38. Mitchell's 3-pointer and Lewis' fastbreak basket made it a 13-0 run for the Cardinals.

Kennard and Ingram had 3-pointers to help push the Blue Devils to a 56-49 edge.

The Cardinals responded with the next six points and had an empty possession that would have given them the lead. Snider's three-point play put Louisville on top at 58-57 at the 6:13 mark for its first lead since 2-0.

Ingram went 4-for-4 on free throws during a 39-second stretch to give Duke a 66-61 advantage.

"A happy, tired locker room," Krzyzewski said, "because we know we beat a great team."

Allen didn't score in the game's final 19 minutes.

Louisville's offense was up and down. Snider scored all of his points in the second half before fouling out at the 2:01 mark.

The Blue Devils held Lee, who averages a team-high 17 points per game, to 3-for-15 shooting from the field.

"They just really pressured him," Pitino said. "They made him shoot quick. He was rushing things."

Duke led 35-24 at halftime, buoyed by a strong surge at the game's beginning.

Allen had 16 first-half points despite missing a 3-point attempt at the buzzer.

Duke bolted to an 11-2 lead, feeding off energy from a frenzied atmosphere.

Lee made only two of 10 first-half shots from the field. That was part of the Cardinals' 31.3 percent shooting in the first half.

There was nearly a three-minute stretch midway through the first half when neither team scored with Duke leading 21-18. The Blue Devils followed with another burst, and Allen scored eight of Duke's final 14 points of the half.

NOTES: The game was the 1,000th Duke men's basketball contest at Cameron Indoor Stadium. Duke is 844-156 in the building. ... This was Louisville's first road game since its self-imposed postseason ban based on an investigation into allegations of NCAA rules violations. ... Duke also had a home game last year against a team that had self-imposed a postseason ban when Syracuse visited in February. ... Earlier Monday, Duke freshman G Luke Kennard was named the ACC Rookie of the Week. It was the fourth time a Duke player received that honor this season, with the other three going to F Brandon Ingram. ... The Cardinals wore special black retro uniforms with elements from the 1980s Louisville teams. ... Louisville goes to Notre Dame on Saturday. ... For Duke, the stretch of ranked foes includes a visit Saturday from Virginia and next week's game at North Carolina before a rematch at Louisville.