DeAngelo Stewart made two free throws with 2.9 seconds left to make it a three-point lead, and Konchar picked off the ensuing inbounds pass to seal the biggest win in school history.
Konchar had 15 points and 11 rebounds.
The Mastodons (3-2), who made the move to Division I in 2001-02, had lost all nine previous games against ranked teams and hadn't even played a Top 25 opponent in nearly four years. But on their home court, with crimson-and-cream clad fans all around, Indiana-Purdue-Fort Wayne trailed for only 90 seconds against an in-state power and pulled off the biggest stunner of this early college basketball season in style.
Indiana (3-1) was led by Thomas Bryant with 18 points and Robert Johnson with 16. James Blackmon Jr., the Big Ten's second-leading scorer, finished with 13 points.
The Hoosiers forced overtime by closing regulation on a 13-3 spurt to make it 65-all. And despite allowing only two baskets in the final 14½ minutes, they still couldn't find a way to win.