AP Photo Michigan guard David DeJulius (0) attempts to drive past the defense of Louisville’s Ryan McMahon (30) during the second half Tuesday.

LOUISVILLE, Ky. (AP) — Louisville players and coach Chris Mack cared more about protecting the basket against Michigan than defending their new perch atop the rankings.

Fulfilling that priority helped the Cardinals succeed in their season debut as the nation’s No. 1 team.

Jordan Nwora had 22 points and 12 rebounds, and Louisville held No. 4 Michigan to a season-low 26% shooting mark for a 58-43 victory Tuesday night in its first game since returning to No. 1.

The Cardinals (8-0) shot just 37% but their defense stifled Michigan (7-1) much of the night as they earned a signature victory in the Big Ten/ACC Challenge one day after claiming the top spot in the AP Top 25 for the first time in six years. Though their second-year coach has downplayed rankings, the win was significant for a program he has guided back into the national championship discussion following a sex scandal and the school’s involvement in a federal corruption investigation of college basketball.

Players seem more focused on building on it.

“Our season’s not over yet,” Cardinals guard Lamarr Kimble said. “No. 1’s just a number. We’re going to continue to get better.”

As for Mack, he was most satisfied with how his team denied just about everything Michigan attempted while passing or shooting, holding the Wolverines to just better than half their scoring average (82.4 points per game). That mattered on a night when baskets were nearly as hard to come by for the Cardinals.

“The story of the game was just our defensive effort, from the beginning of the game all the way through,” Mack said. “We probably played 38½ minutes as good a defense as we can play, outside of maybe the first minute of the second half.”

The Cardinals kept the Wolverines and first-year coach Juwan Howard from adding another top-10 upset to the ones that helped them enter the Top 25 and match Kansas (1989) for the biggest jump from being unranked in the 70-year history of the poll.

“Give them credit,” Howard said. “They do a great job of defending. Unfortunately, they did a good job of keeping us out of the paint.”

Jon Teske had 18 points and 10 rebounds for the Wolverines, who were seeking their first victory over a No. 1 team since beating Duke 81-73 at home on Dec. 13, 1997.

Michigan opens Big Ten play at home against Iowa on Friday.