The Bearcats fell 84-82 to the Cardinals in the opener at Bearcat Arena on Sunday to fall to 0-3 to start the season.
Northwest began Mark Kellogg's lone season in Maryville with three straight wins a year ago, but this season's Bearcats have now dropped back-to-back contests by single digits.
Ariel Easton was a one-woman wrecking crew in the first half, pouring in 25 points to help fuel Northwest to a 41-40 halftime lead. She finished with a game-high 29 points 9-of-15 shooting.
Ashleigh Nelson and Shelby Mustain also finished in double figures with 16 and 14 points, respectively.
The Bearcats' lead grew to 10 points midway through the second half, but Aerial Smith's layup gave William Jewell (3-1) the 84-82 lead with six seconds left.
Nelson missed the go-ahead three-pointer as time expired.