Duke's Grayson Allen received a Flagrant 1 after he tripped a Louisville player. It looks like Allen was trying to prevent a fastbreak after he missed a shot and ended up on the floor.
They're so smart at Duke. Although Allen could have very well believed he was fouled on his awful layup attempt and took out some revenge of his own.
Either way Duke, who is currently unranked, was able to beat ranked Louisville, who has some problems of their own.