Jerick McKinnon knows he's got experience and speed on his side in the Vikings' open competition to replace departed icon Adrian Peterson.

The former third-round draft pick, in his fourth summer practicing in Mankato and just barely 25 years old, has been with the Vikings at least two years more than any of the running backs on the roster. And when asked which of Minnesota's hopeful starters, from banged-up free-agent addition Latavius Murray to ex-Tennessee Titans reserve Bishop Sankey, boasts the quickest legs, he was quick to answer.

"Me," McKinnon said, hiding a smile as third-year safety Anthony Harris stood by his side, eager to hear the running back's opinion. "I'm not going to say I'm slower than anybody."

But fastest legs don't always equate to starting legs, and that has been exemplified during all but a handful of first-team practice reps at camp, where rookie Dalvin Cook, amid high praise from coach Mike Zimmer and an increasing national spotlight, has taken a clear lead in the fight for the No. 1 running back role.

Dalvin Cook is still in line to start for the Vikings. USATSI

McKinnon was in the mix during Wednesday's morning walk-through, especially as the Vikings deployed various goal-line packages and sent him out wide behind the receiving trio of Stefon Diggs, Adam Thielen and Laquon Treadwell. But even he acknowledged the big-name rookie has what it takes to do damage early on.

"He's picking up everything well," McKinnon said. "He can catch out (of) the backfield, he's really patient, he reads the box really well. Everybody's seen him at Florida State and what he can do, so I know everybody's excited about him, and it's exciting to watch."