The Buckeyes rallied from an early deficit, but the Wildcats pulled it out.
Program victory No. 2,500 will have to wait another day for Ohio State baseball. The Buckeyes dropped their Big Ten opener, 6-5, to Northwestern on Friday night in Columbus.
Ohio State fell to 12-7-1 on the season, and had a five-game winning streak snapped.
Senior third baseman Nick Sergakis extended his streak of reaching base safely in every game thus far in 2016, going 3-for-4 at the plate with a two-run home run and an RBI single in the losing effort.
Northwestern got on the board in the top of the first thanks to some sloppy play by Ohio State.