Jake Koch had 14 points and 10 rebounds and three blocks to lead Northern Iowa to a 61-54 victory against suddenly-skidding Creighton on Wednesday night.
Seth Tuttle and Deon Mitchell added 12 points each for the Panthers (15-11, 8-6 Missouri Valley).
Doug McDermott had 15 points and 12 rebounds for Creighton (20-6, 9-5), which dropped its third straight.
At the start of last week, the Bluejays were ranked No. 16 but tumbled out of the Top 25 after losses to Indiana State and Illinois State.
Once in the driver's seat for the MVC regular-season title, Creighton has fallen into a second-place tie with Indiana State.
Both schools are a game behind Wichita State, which has won two in a row after a three-game losing streak.
Matt Bohannon's 3-pointer with 3:16 remaining gave Northern Iowa the lead for good, 52-49.
After that, the Bluejays shot 1 for 5 from the floor - McDermott's dunk at the buzzer was the only successful attempt - and went 3 for 8 from the line.