GREEN BAY – It was the kind of play that makes everyone in the film room sit up straight and pay attention.
In the second quarter of the Vikings' opener last week against the 49ers, running back Dalvin Cook took a handoff up the middle, bounced off a couple of tacklers and powered through a couple more.
The play didn't end as desired for Cook, as he had the ball punched out from behind, and the Vikings lost the fumble. But the 15-yard gain was a taste of what the 5-foot-10, 210-pound Cook adds to the Kirk Cousins-led offense that Minnesota will bring to Lambeau Field on Sunday.
"That's definitely one where you see bouncing left-right, left-right and all of a sudden breaking through out of nowhere," Martinez said. "You see that and know that you need to bring your feet, wrap up and get everybody to the ball."
As the Packers prepare for their first of two showdowns with the Vikings this season, they've already seen the rest of Minnesota's offensive arsenal multiple times. Receivers Stefon Diggs and Adam Thielen, along with tight end Kyle Rudolph, are familiar foes. Cousins is, too, having faced Green Bay as Washington's QB in the 2015 playoffs and 2016 regular season.
The new weapon in the mix is Cook, a second-round draft pick last year who arrived with a bang. Then his rookie season was cut short by a torn ACL in Week 4, before the Packers and Vikings met.
The aforementioned tackle-breaking run reminded some observers of former Minnesota star Adrian Peterson, and while comparisons to a future Hall of Famer are way too premature, consider this: Before last year's injury, Cook's 288 rushing yards in his first three NFL games topped Peterson's total, the previous Vikings rookie record, from the start of his career.
"He's a powerful, violent runner, but he's also really elusive," defensive tackle Kenny Clark said. "I think he has great balance through the hole, great balance when guys hit him."
The Packers were back at practice Thursday afternoon ahead of Sunday's divisional matchup with the Minnesota Vikings.
Cook has returned no worse for wear from the ACL, and he posted 95 yards from scrimmage (40 rushing, 55 receiving) in Minnesota's Week 1 victory over San Francisco.
The only Packers defender who has any experience against Cook is rookie cornerback Jaire Alexander, whose college team (Louisville) plays in the same Atlantic Coast Conference division as Cook's (Florida State).
"Went up against him sophomore year," Alexander said. "Just gotta hit him low."
Easier said than done against a player with such quick feet. The Packers' open-field tackling in their opener against the Bears was fairly solid, especially on some key third downs in the second half.
There's a good chance Cook will test Green Bay in that regard as he continues to develop into the three-down back the Vikings drafted him to be.
Last year after Cook's injury, Minnesota went to a combination of Latavius Murray as a runner and Jerick McKinnon as a pass catcher out of the backfield. While Murray stepped in for 11 carries last week, it may not be long before Cook takes a larger and larger percentage of the snaps because he's the most complete, and dangerous, of the Vikings' backs.
"Obviously he's a strong runner, runs behind his pads," linebacker Clay Matthews said. "He does a good job in the pass game, too, a lot of screens, scatting out of the backfield.
"He's a guy you need to have your eye on, especially when they try to get him into space. Having him healthy helps their offense out and gives them another playmaker on that side."
San Francisco clamped down on Cook in the second half last week, limiting him to just 10 carries for 18 yards (plus one reception for 8 more) after his strong start. The Packers would love to contain him from the get-go in similar fashion.
But touching the ball 22 times total (16 rushes, six receptions) is a hefty workload for anyone playing his first game since last September. New quarterback or not, it might be just the beginning of where this Vikings offense is headed.
"I think he's a big-time player," Head Coach Mike McCarthy said. "He looks like he's back, full-steam ahead."