The Wildcats (15-7, 4-6 Big Ten) led by five at the half, but Northwestern limited Michigan to 22 points and just six field goals in the second half.
Manny Harris, the Big Ten's leading scorer, was held to 11 points -- eight below his average. He was only 4 for 14 from the field for the Wolverines (11-11, 4-6), who lost for the fourth time in five games.
DeShawn Sims, Michigan's second-leading scorer at 17.6 points, managed only four points. The Wolverines were only 6 for 25 from the field in the second half.
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Guard Naz Mitrou-Long, whose 2015-16 season ended in December due to hip problems, has been granted a hardship waiver for the coming season, Iowa State said.
As the Sooners look to life without superstar Buddy Hield and his sidekicks, it's clear their unseasoned players will need to grow up fast.