DURHAM, N.C. ? Top-ranked Duke needed about 20 minutes to find its form.

J.J. Redick scored 23 points, and freshman Luol Deng matched his career high with 22 to help Duke overcome a slow start and beat Clemson, 81-55, Sunday night.

“They came out tonight believing that they were going to win, and they showed it in the first half,” Deng said. “They prepared really well. … In the first half, we were lacking a little bit, but we picked it up, and we got a great win.”

Deng also had seven rebounds and three steals for the Blue Devils (20-1, 9-0 Atlantic Coast Conference), who reached 20 wins for the eighth straight season. Duke has won 17 consecutive games overall and 38 in a row at Cameron Indoor Stadium.

The Blue Devils extended their dominance of the Tigers (9-11, 2-7), winning their 17th straight meeting and 13th in a row by a double-digit margin. The Tigers haven’t beaten the Blue Devils since January 1997.

Clemson is 4-53 all-time in Durham and hasn’t won here since January 1995.

Duke was coming off an emotional 83-81 overtime win against rival North Carolina Thursday night, and the Blue Devils looked flat early. They missed 18 of their first 26 shots and didn’t play the lock-down defense that marked their winning streak.

But the Blue Devils used a 14-0 run to get some breathing room, then maintained their double-digit lead in a grind-it-out game that featured 49 personal fouls.

“Sometimes when you win a game like (Thursday) … at times it’s a huge challenge to come back,” Duke coach Mike Krzyzewski said.

The Blue Devils didn’t get a boost of energy from their famed fans, either.

The Cameron Crazies did not fill up the student section — a rare sight for ACC games — and Krzyzewski yelled and motioned for them to get loud as he ran off the court at halftime.

“I don’t know what to do exactly, but I’m going to try to do something because (the environment) needs to be better,” Krzyzewski said. “We shouldn’t have empty seats. How can we have empty seats at Cameron? … We’re the No. 1 team in the country. After winning one of the most unbelievable games, it’s disappointing.”

The Tigers, meanwhile, showed no early signs of rust from a weeklong layoff since stunning the Tar Heels, 81-72, Jan. 31. They fought Duke on every possession and got solid play from Sharrod Ford (19 points) and Shawan Robinson (18 points) to hang around, but never could make a serious run in the second half.

The teams were tied at 27 before Duke put together a quick spurt, scoring nine straight points in the final 90 seconds of the first half.