In the series AZ, BY, CX, DV, EV, which pair does not follow the pattern?

Explanation

1. 01

   First letters A, B, C, D, E move forward one place: all fine.

2. 02

   Second letters should move back one place: Z, Y, X, W, V. The fourth pair has V instead of W.

3. 03

   So DV is wrong; it should be DW (D and W are opposite letters: $4 + 23 = 27$).