The third-ranked Buckeyes (8-1) briefly turned a four-point halftime deficit into a four-point lead early in the second half, but the 11th-ranked Blue Devils (6-1) responded with the next eight points to take a lead they would not relinquish.
Sarah Schulze gave the Buckeyes a 41-37 advantage with a three-pointer at the 16:59 mark, but Ohio State would score only three of the next 17 points in the contest to fall into a hole out of which they could not climb.
Prahalis, the Buckeyes' point guard who entered the game second in the nation averaging 10.0 assists per game, had eight helpers and eight turnovers.
She picked up her fourth foul at the 12:02 mark with Duke leading 53-49, and the Blue Devils quickly upped their lead to 12 with eight points in a row.
The Buckeyes later got back within five, 66-61, at the 5:56 mark after two free throws by Lavender, but that was as close as they would get.
Jasmine Thomas made a trey on the next Duke possession to start a 12-0 run that put the game away.
Thomas led all scorers with 29 points.
Lavender had 18 rebounds but struggled to find the range from the floor. She missed 11 of 18 shots from the floor.
Overall, Duke made 50 percent of its field goals (33 for 66) while the Buckeyes were only 21 for 57 (36.8 percent).
Turnovers hurt the Buckeyes as well. They gave the ball away 21 times leading to 27 Blue Devil points.
Ohio State fell to 0-3 all time in the ACC/Big Ten Women's Basketball Challenge.