Portland found that out the hard way Sunday night as the fourth-ranked Blue Devils rolled over the Pilots 84-43, forcing 19 turnovers, blocking 14 shots and recording 12 steals.
"I told Coach (Mike) Krzyzewski after the game that was probably the best defense I've ever seen and I known it's the best defense my players have ever seen," said Portland coach Michael Holton, a former guard for UCLA. "They suffocated us from the opening tip."
Luol Deng scored 15 points and had nine rebounds as Duke held Portland to three first-half baskets in the lopsided win.
"We better play good defense because we're not hitting all our shots," Krzyzewski said. "In some respects it's a blessing that it hasn't been as easy offensively because we've concentrated even more on defense. The kids really believe they have to do it."
Deng came off the bench for the first time this season, but the freshman didn't miss a beat, scoring 11 of his points as the Blue Devils built a 28-point halftime edge.
In a 26-second span in Duke's masterful first half, Deng blocked a shot, hit a 3-pointer and then drew a charge, showing of his all-around game.
Duke (6-1) didn't have much trouble with its overall game after an eight-day layoff for exams, extending the nation's longest home winning streak to 31.
Eugene Jeter led the Pilots with 10 points, but was 3-for-15 from the field.
Meanwhile, Portland (5-2), which came in with a five-game winning streak, missed 16 of its first 17 shots and was just 3-for-28 with 12 turnovers in the opening 20 minutes against Duke's pressuring defense.
At one point, the Pilots went close to nine minutes without a basket as Duke went on runs of 12-2 and 15-2 to open up a big margin.
The Pilots came in third in the nation in 3-point shooting, but the Blue Devils extended their defense beyond the arc and Portland was never able to get into its offense most of the night.
"To be quite frank with you I was really concerned about this game," Krzyzewski said. "They had beaten Oregon State and New Mexico on the road and they took it to Nevada. We were fortunate that we were able to take away their strength."
Two of Portland's six 3-point attempts early were air balls that didn't come close to the basket.
Things were worse inside for the Pilots, who had 11 shots blocked in the half - six by Shelden Williams, who hurt his left foot late in the period and had to leave the game twice as Duke took a 40-12 lead at the break.
Duke's starting center, who sprained the same ankle two days ago in practice, didn't return to the bench in the second half.
Krzyzewski said if it was an ACC game, Williams probably would have been able to go back in.
The 12 points were the ninth-fewest Duke has allowed in a half since 1955.
Duke's block total was the second-best in school history behind the 17 against Virginia in 1999.
"We did an amazing job on the defensive end," Duke captain Chris Duhon said. "Our big guys did a great job of protecting our goal and our perimeter kept guys in front of them and made them take tough shots."