Dalvin Cook and C.J. Ham are as different as saltwater and salted sidewalks.

Dalvin Cook speaks with a languorous southern drawl. C.J. Ham could teach diction at a prep school.

Cook has been a star since high school, where he made his bones as a spectacular running back in the recruiting hotbed of Miami, and was a top recruit at Florida State. Ham was similarly productive playing high school football in the hockey hotbed of Duluth and college football at a small school in South Dakota.

Cook was a first-round talent drafted in the second round. Ham went undrafted.

Now they're proving that opposites attract tacklers. As Cook emerged as the key to the Vikings offense this season, Ham became his bodyguard and snowplow. When the Vikings travel to San Francisco, they'll be roomies at the hotel and besties on the field, and perhaps a key to victory.

"We've been close ever since he got here,'' Ham said. "I've been in the league one year longer than he has, but I was on the practice squad. His rookie year, at rookie minicamp, that was my first time playing fullback, and it started with him in the backfield.

"He told me then that he had a fullback in college and he loved his fullback. Right away, I knew that we were going to have a good relationship.''

When the Vikings decided to build their offense around Cook this offseason, Ham's responsibilities increased. Saturday, Ham and 49ers fullback Kyle Juszczyk will advocate for a position endangered by modern passing offenses and revived by believers in power running, such as Gary Kubiak, Kevin Stefanski and Kyle Shanahan.

"It's pretty fun,'' Ham said. " 'Juice' is respected around the league. He's a great player. I watch a lot of film on him. He does a lot of special things.''

Their teammates rave similarly about Cook and Ham, while busting stereotypes, noting that Ham's athletic ability may be as underrated as Cook's savvy.

"C.J. is just a relentless monster of a guy,'' running back Alexander Mattison said. "Man, that guy is probably the most athletic big guy that I've ever met or been around. So to have someone like that, who is super athletic, super tough, super physical, leading the way for Dalvin, who is super athletic and physical himself, that's a combination that you can't beat.''

"Both have vision,'' linebacker Eric Kendricks said. "A fullback has to have vision, just like a running back. You have to see things before they happen.

"Most important, they're both tough [guys]. Those are not the easiest positions to play, physically. One position, you hit every play, and the other position, you get hit every play. Those guys inspire me.''

"It's obvious by the way that C.J. blocks for Dalvin that he would give his arm and his leg for Dalvin,'' defensive end Ifeadi Odenigbo said. "The fact that they're roommates, too, just shows the chemistry they have. C.J. is such an unselfish player, and their dynamic is pretty special.''

The Vikings talked all offseason about building their team around a power-running offense featuring Cook, and he has proved to be just as important as imagined. The Vikings have lost six games. In their past five losses, Cook has either not played or rushed for fewer than 72 yards.

Before the playoff game in New Orleans, when he rushed 28 times for 94 yards and two touchdowns, Cook had hadn't rushed for more than 62 yards since Nov. 10 in Dallas.

He refused to call the damage to his shoulders "injuries,'' saying "I was just banged up,'' and that the coaches were resting him "for the stretch run.'' Whether that's true or not, the Vikings benefited from having a fresh Cook in New Orleans, and will likely build another game plan around him this week.

"He's the type of back who makes everybody on the field better,'' Ham said. "The way he plays, the way carries himself, the way he leads, I would run through a wall for him.''

Which is pretty much the job description.

Jim Souhan's podcast can be heard at TalkNorth.com. On Twitter: @SouhanStrib E-mail: jsouhan@startribune.com