Florida Gulf Coast lost for the first time this season Thursday night, falling to Stetson 70-52.
Duke is the only unbeaten women's team left in Division I basketball.
Sarah Hansen scored 16 points to lead the Eagles, who had won their first 14 games.
The defeat came a game after the Eagles set an NCAA record for 3-pointers with 55 shots in a 87-52 victory over Mercer on Monday.
Florida Gulf Coast, off to its best start since starting to move to Division I in 2007-08, shot 7 for 31 from behind the arc on Thursday night.
The Eagles, who have beaten Seton Hall, Virginia Tech, and Montana had received one vote in the poll the last few weeks. Since they are still transitioning to Division I, they aren't eligible yet to play in the NCAA tournament.