The top-seeded Lady Lions (25-4) had their difficulties in this one after earning a first-round bye and their second straight regular-season title with a 14-2 conference record. But they went on a big run early in the second half to break a tie and earn a spot in Saturday's semifinals against the Michigan-Michigan State winner.
Bentley was 8 of 13 from the field. Lucas, the Big Ten player of the year, hit three 3-pointers.
Nikki Greene scored 17, and the Lady Lions shook off a slow start to shoot just over 49 percent in the game.
Tayler Hill scored 23 for Ohio State (18-13) and became the fifth Buckeyes player to hit the 2,000-point mark. She now has 2,015 in her career, but it was a tough night overall, even though she tried to inject some suspense as the game wound down.
Hill hit back-to-back 3-pointers and added a free throw after being fouled on another attempt from long range, pulling the Buckeyes within 73-66 with 42 seconds left. But she was just 7 of 21 from the field after scoring 25 in the first round against Minnesota.
Amber Stokes had 18 points and five steals. Ashley Adams added 13 points and eight rebounds, but the ninth-seeded Buckeyes came up short after winning seven of their previous nine games.
With an experienced and explosive backcourt led by Bentley and Lucas and the depth to play just about any style, Penn State believes it has the makeup for a long postseason run. Winning the conference tournament would be a significant step. That's something the Lady Lions haven't done since 1996.
They came in as the second seed two years ago and lost to Ohio State in the final, and last season, Penn State earned the top seed, only to fall to fourth-seeded Purdue in the semifinals.
The Lady Lions finally started to build some momentum early in the second half, going on a 14-2 run to break a 39-39 tie.
They scored 10 straight, starting with Bentley's fast-break jumper. Lucas followed with back-to-back 3s, pumping her fist after she got knocked to the floor by Stokes knocked her to the floor on the second one. She missed the foul shot, but Mia Nickson added two free throws to make it 49-39 with 14:05 remaining before Ferguson scored inside for Ohio State.
Nickson answered with a jumper, and Greene scored on a layup to put Penn State ahead 53-41 with 12:24 left.