HALFTIME: Duke 30, Louisville 20

LOUISVILLE, Ky.—Saturday's contest has turned into a defensive battle, and after 20 minutes at the KFC Yum! Center, the Blue Devils are more than holding their own.

No. 4 Duke held No. 6 Louisville scoreless for more than five minutes to build up a double-digit lead and carries a 30-20 advantage into the locker room. A major switch on the defensive end of the floor has paid dividends for the Blue Devils, but the Cardinals haven't helped themselves, shooting just 22.6 percent.

The biggest question mark coming into the game was how Duke would handle Louisville guards Terry Rozier and Chris Jones on the defensive end. The duo thrives in ball-screen action, which Miami used time and again in Tuesday's 16-point win at Cameron Indoor Stadium. In the early going, the Blue Devils countered with some 2-3 zone, which forced the Cardinals into some errant lob passes and several 3-pointers.

Louisville is one of the poorest long-range shooting teams in the ACC, but the Cardinals have been cold from all over the court in the first half. Both Jones and Rozier drilled triples in the first eight minutes to stake the Cardinals to a 10-6 lead. On made baskets, Louisville has looked to apply full-court pressure, but it hasn't caused Duke much trouble thus far.

The Blue Devils have looked to get Jahlil Okafor plenty of touches, but Rick Pitino's 2-3 zone has forced Duke to swing the ball around the floor looking to set up a good look. Amile Jefferson led the charge with 10 points in the first half. Okafor finished with just four points on three shots.

Here are some observations from the first half:

• Tyus Jones tweaked his right leg early in the first half, but returned following the under-12 timeout.
• The Blue Devils had not shot the ball well from long range in ACC play, but got a pair of corner triples from sophomore Matt Jones to knot the score at 12-12 with 8:28 to play and force Pitino to call a timeout.
• Louisville is shooting extremely poorly but winning all of the loose balls, commanding a 10-1 advantage on the offensive glass. The Cardinals haven't turned those into baskets though, with just three second-chance points in the opening frame.
• Despite just four points from Okafor, Duke has built up a strong edge in the paint, keyed by Jefferson, leading 16-6 in that category.
• Montrezl Harrell was all over the glass for Louisville, pulling down seven rebounds, but didn't score until the last possession of the first half, when the junior beat the buzzer with a home-court bounce on the rim.
• Justise Winslow extended a six-point Duke lead to nine with a three-point play in transition with 3:18 remaining, drawing contact as he went up for a dunk and getting a friendly roll on the rim.