C.J. Cox scored 21 of his 27 points in the second half, including a go-ahead 3-pointer with 48 seconds left that helped No. 15 Purdue edge Nick Martinelli and Northwestern 70-66 on Wednesday night. Cox outlasted Martinelli in a memorable duel in the final minutes, sending Purdue to a sorely needed victory. The Boilermakers (23-7, 13-6 Big Ten) had lost two in a row and three of four overall.