According to my predictor, the most likely upsets at the 4, 3, 2, and 1 levels:
Ohio (13) over Michigan (4) [Louisville close behind]
Belmont (14) over Georgetown (3) [FSU close behind]
Lehigh (15) over Duke (2) [By far the weakest #2 seed]
Lamar (16) over UNC (1) [Syracuse close behind]