It appears the teams are trending in opposite directions come 2015.

The Vikings have an emerging quarterback in Teddy Bridgewater, but more importantly, have Adrian Peterson back in the mix at running back. Their defense also boasts some young talent in Trae Waynes, Anthony Barr, Xavier Rhodes and Everson Griffen. Could this be the year Minnesota challenges Green Bay for supremacy in the NFC North?

The 49ers endured arguably the toughest offseason for a team, with a number of key players retiring or leaving in free agency. Combine the roster turnover with a new head coach and it's hard to envision a better season after an underwhelming 2014 campaign.

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Here are three keys to the game for both the Vikings and 49ers.

VIKINGS

1. Let Peterson loose

Although perfectly healthy, Peterson was unable to play in 15 out of 16 games last season while relegated to the exempt/commissioner's permission list. He's already one of the most gifted runners the NFL has seen, but there's a real chance a well-rested, 30-year-old Peterson returns in incredibly rare form. The 49ers will be the unfortunate first ones to find out.

2. Take shots downfield

Bridgewater has established himself as a cerebral quarterback after one year. His job should get easier now that handing off to Peterson is an option again. Bridgewater is likely to lean on high-percentage plays, such as underneath strikes to tight end Kyle Rudolph. However, he should also put his new deep threat, speedy wideout Mike Wallace, through a thorough test in San Francisco on Monday night.

3. Be aggressive on defense

The Vikings' defensive front should turn up the heat against San Francisco's offense. The D-line is fueled by its youth; tackles Sharrif Floyd and Linval Joseph, as well as Griffen, are all 27 years old or younger. Barr, a top 10 pick in last year's draft, is another fresh talent who can make plays in the opposing backfield. If the front seven can put enough pressure on 49ers quarterback Colin Kaepernick, the Vikings can force him to make a couple critical mistakes.

49ERS

1. Protect Kaepernick

In 2014, the 49ers offensive line allowed 52 sacks, tied for third most in the league. The Vikings recorded 41 sacks, tied for ninth. With the 49ers introducing two new starters along the line in Jordan Devey (right guard) and Erik Pears (right tackle), it doesn't look pretty on the surface. But if the 49ers expect Kaepernick to limit his mistakes, giving him some time to throw in the pocket is paramount.

2. Run the ball

If the Vikings defense can be beat, it's via the ground. Last season, Minnesota ranked 25th in rushing yards allowed per game (121.4). On the other side, the 49ers ranked fourth at 136.0 rushing yards per contest. With Frank Gore in Indianapolis, the 49ers have high expectations for Carlos Hyde to be their bell cow in 2015.

3. Stop Peterson

The 49ers lost a number of key players on defense, particularly in their linebacking corps. But they do return NaVorro Bowman, who looked healthy in the preseason. Expect Bowman to have a key role in determining whether Peterson has a big game in his return to the field.