Devin Oliver of the Dayton Flyers reacts after defeating the Syracuse Orange at the First Niagara Center in Buffalo, N.Y., March 22, 2014. (Elsa/Getty Images)

It's become the tournament of underdogs.

Small colleges, Ivy League programs and universities with no national name recognition have entered this year's NCAA college basketball tournament and toppled the powerhouse competition.

It began on the first day of March Madness, when Mercer University of Macon, Ga., upset tournament perennial favorite Duke University in the first round of competition, busting thousands of brackets in the process. The same day, Dayton University edged out Ohio State 60-59.

But for those that meticulously plotted their brackets based on powerhouse schools like Kansas, Syracuse and Kentucky, Mercer and Dayton were just the beginning.

In the five days since the tournament started, dozens of upsets have wracked the tournament brackets, giving little-known schools with names like Stephen F. Austin University the chance to wow the nation in a first-round upset of fifth-seed Virginia Commonwealth University. They later lost to UCLA.

Harvard brainiacs also got their athletic moment in the spotlight, beating No. 5 seed Cincinnati before losing to Michigan.

The underdogs have shaken things up in the tournament world. Sweet 16 play kicks off on Thursday.