Kelsey Mitchell scored 21 points to lead the victors. Shayla Cooper had 12 and Sierra Calhoun added 10.
Fairmont grad Makayla Waterman added two points and two rebounds for the Buckeyes.
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Ohio State heads into the postseason having won 11 in a row, including a 98-87 triumph over then-No. 2 Maryland last Monday night that pulled the Buckeyes into a first-place tie with the Terps.
Maryland crushed Minnesota earlier Sunday to clinch a share of its third Big Ten title in as many years as a league member, but the Buckeyes get the No. 1 seed in the Big Ten tournament thanks to their head-to-head win.
That begins Wednesday in Indianapolis.
Ohio State will play at noon Friday against the winner of the game between the No. 8 and 9 seeds.
The Buckeyes will be looking for their first tournament title under McGuff, a Badin High School grad in his fourth season at the helm in Columbus.