According to NFL Network's Tom Pelissero, RB Dalvin Cook (shoulder) was a full participant in practice on Thursday for the Minnesota Vikings. He was a non-participant in practice on Wednesday. (Tom Pelissero on Twitter)
The Vikings are in London right now for their Sunday game against the New Orleans Saints, and Cook was a full participant as he nurses a shoulder injury resulting from a dislocation that kept him out of the latter portion of Sunday's game against the Detroit Lions. This is a strong sign for him to play, an injury he has suffered and played through multiple times. In the event that he doesn't play, RB Alexander Mattison becomes an RB2 candidate, but if Cook is a go, Cook is a starter and Mattison goes to benches.