I'd definitely start Sproles, such a good matchup. So the last spot is between Mathews and Mendenhall. I'd go with Mathews as he is going against a bad KC rushing defense while NE is in the upper half of rush def.
1QB, 2RB, 2WR, 1 WR/TE, K, DEF
Standard 12-Man Auction League
QB - C. Newton, J. Flacco
RB - R. Rice, M. Jones-Drew, M. Tolbert, C.J. Spiller, D. Karim
WR - L. Fitzgerald, W. Welker, J. Graham, L. Moore
K - S. Gostkowski
DEF - Jets, Titans