Tournament Challenge: 5.7 percent perfect

Just four games into the tournament, only 5.7 percent of the 11 million-plus brackets in ESPN's Tournament Challenge are still perfect after wins by Wisconsin, Pittsburgh, Harvard and Dayton.

Harvard became the second double-digit seed to pull off a win Thursday afternoon, and 31.4 percent of brackets (including President Obama's) had the 12-seed Crimson over 5-seed Cincinnati. They were a more popular pick than 11-seed Dayton, taken in just 19.7 percent of brackets to beat Ohio State. Also, 8.8 percent of brackets had both Dayton and Harvard pulling off the upsets.