LOUISVILLE, Ky.—At intermission, the second-ranked Blue Devils find themselves in an unfamiliar position, at least for road games, as they trail the No. 16 Cardinals 38-29 at the KFC Yum! Center. Here are five observations from the opening 20 minutes:

Player of the half: Zion Williamson

It feels like a nightly occurrence, but Williamson has been the only consistent thing working for Duke on the offensive end. The Spartanburg, S.C., native has 13 points and seven boards—nearly enough for a first-half double-double—and Williamson has yet to commit a turnover. Plus, the freshman has been effective on the defensive end, switching onto Louisville's guards and keeping them in somewhat in check.

So much for a hot start...

Things could not have gotten much uglier in the game's first 4:34. In the lead-up to the first media timeout of the night, the teams combined for just five points on 2-of-15 shooting from the field. The Cardinals came out in a 2-3 zone that posed some early problems for the Blue Devils, but Duke countered with some pretty solid man-to-man defense of its own. The visitors forced a pair of turnovers, blocked a shot and drew the ire of the Louisville crowd thanks to some no-calls from the officials.

Crashing the glass

With so many missed shots, there were plenty of chances for both teams to get on the boards. For the Blue Devils, it was Williamson leading the way with seven and Cardinal forward Jordan Nwora answered with six of his own as the hosts lead in that category by a 21-20 margin at the break.

Ch-ch-ch-ch-changes

Louisville has thrown Duke off its game a bit, using a variety of different defenses to make the Blue Devil offense think. After the Cardinals began the night in a 2-3 zone, Chris Mack's team switched into a 1-3-1 before ultimately settling into their usual man-to-man. The Blue Devils struggled to get on track from the field, hitting just 36.4 percent of their shots and knocking down only three of their 15 long-distance tries—three days after putting up a stellar 13-of-21 performance from downtown at Virginia.

Problems in the paint

Although Duke has logged 16 points in the painted area, the Blue Devils have not gotten much production from the big man trio of Marques Bolden, Javin DeLaurier and Jack White. That group entered Tuesday night combining for an average of 14.2 points, 13.8 rebounds and 4.1 blocks. Tuesday the threesome has posted two points, three rebounds and zero blocks, and Louisville big man Steven Enoch has exploited them on defense to the tune of 10 points and pair of 3-pointers.