With training camp already underway in Green Bay, Minnesota and Chicago (Detroit begins Saturday), let's preview some of the key position battles and players to watch in the four NFC North training camps.

GREEN BAY

Training camp report dates: Rookies and veterans (July 26).

Location: St. Norbert College, De Pere, Wisconsin.

Key position battle: Cornerback

The Packers had the second worst passing defense in all of football last season, so it's no surprise they went out and signed Davon House in free agency and then drafted Kevin King and Josh Jones in the second round this offseason. Jones is a safety.

House is expected to slot into a starting role, so that leaves Damarious Randall, Quinten Rollins, LaDarius Gunter and King all battling it out for playing roles. King has the kind of size and athleticism that should allow him to push for a starting job right out of the gate.

This is an area the Packers need to drastically improve in 2017.

Newcomer to watch: Martellus Bennett

Aaron Rodgers and Bennett seem like a match made in heaven. Green Bay's passing game is one of the most versatile in football, and Bennett gives Rodgers a security blanket across the middle of the field and a terrific red zone threat.

Bennett caught 55 passes for 701 yards (12.7 average) with seven touchdowns playing with Tom Brady in New England last season. With Rodgers' ability to extend plays, Bennett should have a terrific season.

Rookie to watch: Kevin King

King lit up the NFL Scouting Combine when he ran a 4.43-second 40-yard dash with a 39.5-inch vertical at 6-foot-3 and 198 pounds. He also had the fastest time among cornerbacks in the 3-cone drill and 20-yard shuttle. After the workout, his stock rose. Is he a workout warrior or the real deal?

King wasn't able to participate fully in OTAs because of NFL rules restricting rookies to take part in the offseason training program until their college semester has concluded. How quickly can King acclimate himself to the speed of the game?

Quotable: "I knew there were going to be some growing pains that we'd have to work through," Packers cornerbacks coach Joe Whitt Jr. told the Green Bay Press Gazette of last season's cornerback group. "I didn't think it was going to be as hard as it was."

DETROIT

Training camp report dates: Rookies (July 24) and veterans (July 29).

Location: Lions Training Facility, Allen Park, Michigan.

Key position battle: Left tackle

Losing Taylor Decker for any amount of time is less than ideal for a Lions team that spent considerable resources bolstering its offensive line this offseason.

The hope is Decker can get back on the field sooner rather than later, but in the meantime, someone will have to step up and fill his shoes.

Greg Robinson, the former No. 2 overall pick who the Lions traded for in June, is the most likely candidate. Detroit is hoping a change in scenery and a new scheme might fit Robinson's skill set and allow him to be more of a productive player than he was in Los Angeles.

The fact that Cyrus Kouandjio (NFI) and Corey Robinson (PUP) will start training camp on the sideline also boosts Robinson's chance at winning the starting job.

Newcomer to watch: T.J. Lang

Lang missed the entire offseason training program and June's minicamp recovering from offseason hip surgery. He's a veteran player, so his acclimation back into action should be rather smooth, but he is learning a new offense and has to learn the tendencies and abilities of new linemates, particularly those of right tackle Rick Wagner.

Lang was a Pro Bowl player last year in Green Bay, and should be an instant leader along the offensive line.

Rookie to watch: Jarrad Davis

Davis will be the starting MIKE linebacker Day 1 of training camp, and defensive coordinator Teryl Austin has already entrusted him with calling the defense.

Davis is diligent, smart and brings much needed athleticism to the middle of Detroit's defense. He's expected to make an immediate impact.

Quotable: "I just think that everybody is a little different, asked to do different things in different systems and things of that nature," Lions head coach Jim Caldwell said of Robinson shortly after the Lions acquired him this offseason.

"So, we think he fits well with us and we'll see. He's the kind of guy we're looking for and he'll work at it."

MINNESOTA

Training camp report dates: Rookies (July 23) and veterans (July 26).

Location: Minnesota State University, Mankato, Minnesota.

Key position battle: Running back

Minnesota finished last in the NFL last season in rushing yards and yards per attempt. To combat that problem, the Vikings went out and signed former Raider Latavius Murray and then drafted Dalvin Cook.

Murray missed the offseason rehabbing an injury, and will start camp on the PUP list, but he's averaged more than 900 yards and nine touchdowns the last two seasons. He's the kind of physical runner the Vikings typically like to feature.

Cook is a burner and big-play threat. He'll compete with Murray for the starting role, and at the very least be a nice third-down back.

The Vikings also have their leading rusher last year, Jerick McKinnon, in the mix.

Newcomer to watch: Riley Reiff

Reiff gets back to being a left tackle in Minnesota after being moved to right tackle last season in Detroit to accommodate Decker on the left side. Reiff isn't a Pro Bowl-caliber left tackle, but he's reliable and physical, both important attributes upfront for head coach Mike Zimmer.

A lot is riding on Reiff and fellow free-agent signee, right tackle Mike Remmers, to fill a big need for the Vikings and help that offense catch up with their stout defense.

Rookie to watch: Dalvin Cook

Cook is a balanced runner with quickness, speed and homerun ability. His game is predicated more on elusiveness than raw power, which is a bit of a change from Adrian Peterson over the last decade in Minnesota.

Does his big-play potential shine through right away in Vikings camp? If it does, he could earn a lot of playing time early in his first season.

Quotable: "They've got the upper hand," Murray told the Minneapolis Star-Tribune this offseason about Cook and McKinnon. "They've been out there practicing. Dalvin, he's been in the system. When you're in it, you learn a lot."

CHICAGO

Training camp report dates: Rookies (July 19) and veterans (July 26).

Location: Olivet Nazarene University, Bourbonnais, Illinois

Key position battle: Receiver

Who is the No. 1 receiver in Chicago these days following the departure of Alshon Jeffery to Philadelphia via free agency? Former first-round pick Kevin White certainly has the skillset, but he first has to prove he can stay on the field, which is something he hasn't been capable of his first two seasons in the league.

Cameron Meredith was a nice second option for the Bears last season, but that's probably more of what he is.

Then there's a collection of veteran players looking for a fresh start. That group includes: Victor Cruz, Markus Wheaton, Kendall Wright and Rueben Randle. They'll battle Deonte Thompson and Josh Bellamy for roster spots and roles.

It should be a nice competition to watch throughout Bears camp.

Newcomer to watch: Prince Amukamara

The Bears moved on from No. 1 cornerback Tracy Porter and signed Amukamara and Marcus Cooper to hefty free-agent deals as starters.

The Bears are banking on Amukamara's experience to help make a difference in the back end of their defense. Chicago cornerbacks have combined for only 10 interceptions over the last two seasons.

Rookie to watch: Mitchell Trubisky

Mike Glennon signed a three-year, $45 million contract this offseason to be the Bears' starting quarterback, only to see the team trade up to take Trubisky No. 2 overall in the draft.

Trubisky is obviously the future of the franchise, but will that be in 2017, 2018 or beyond? The answer to that question will be determined in training camp and the preseason.

Quotable: "We've added pieces – probably the most noticeable would be the secondary – with experience, guys that have played," Bears head coach John Fox told the Chicago Sun-Times earlier this offseason. "That wasn't necessarily a strength of ours the year before ... There's more experience, more competition in every spot."