With Latavius Murray (ankle) and Jerick McKinnon (leg) sidelined, Cook dominated first-team work Saturday at the first full-pads practice of training camp, ESPN.com's Kevin Seifert reports.
Murray is rehabbing from surgery and hasn't practiced since signing in March, while McKinnon was healthy throughout the offseason until suffering a seemingly minor injury at Thursday's practice. Vikings coach Mike Zimmer suggested Cook has taken advantage of the early opportunity, though the rookie still figures to split first-team work with McKinnon when the veteran returns to practice. Murray is also expected to compete for a major role upon his return, which doesn't seem to be imminent.