Freshman Jared Sullinger hit a free throw with three seconds left, as No. 1 Ohio State lost a double-digit lead before beating pesky Northwestern 58-57 on Saturday at Evanston, Ill.

The top-ranked Buckeyes (22-0, 9-0 Big Ten) let a 51-39 lead slip away, then saw the Wildcats (13-8, 3-7) tie the game at 57-57 on Michael Thompson’s floater with 1:33 to go.

Northwestern had a chance to take the lead inside the final 30 seconds, but a steal by David Lighty gave the Buckeyes the ball, and Sullinger was fouled on the low right block as he made a strong move to the hoop by Alex Marcotullio.

Sullinger missed the first free throw but made the second. Northwestern’s Drew Crawford missed a 3-point heave as time expired.

Up 27-25 at halftime, Ohio State scored 14 of the first 18 points of the second half. Sullinger and William Buford scored six points each during the run, and two Buford free throws with 14:07 to go made it 41-29 Buckeyes.

But the Wildcats rallied trailing 51-39 with 8:25 left. A 16-3 run, capped by Thompson’s 3-pointer with 3:53 remaining, gave Northwestern a 55-54 advantage. Ohio State answered with Jon Diebler’s 3-pointer with 3:38 left to move in front 57-55.

Sullinger led Ohio State with 21 points. The Buckeyes shot 56.8 percent from the field. Thompson scored 16 to pace Northwestern.