Kirk Cousins and Case Keenum made their preseason debuts as the Minnesota Vikings defeated the Denver Broncos, 42-28, at Mile High Stadium in Denver on Saturday night. 

Cousins was composed and efficient in his lone drive captaining Minnesota's offense, while Keenum failed to find a rhythm against the team he led to the NFC Championship Game last season. 

Here's a look at the big takeaways from the opener.  

Stefon Diggs Emerges as Kirk Cousins' Early Favorite Target

Minnesota's No. 1 offense was on the field for eight plays Saturday night. 

As it turns out, that was enough to witness the steady chemistry that has developed between Cousins and No. 1 wide receiver Stefon Diggs to this point in the preseason. 

During the Vikings' opening eight-play, 75-yard scoring drive, Cousins targeted Diggs three times to the tune of 35 yards, including an eye-opening 28-yard hookup down the right sideline: 

Three plays later, Cousins went back to Diggs on a quick one-yard slant to hand the Vikings an early lead: 

And considering Diggs has developed on a lofty trajectory that warranted a $72 million contract extension, it will come as a surprise if he doesn't cross the 1,000-yard threshold for the first time in his career and threaten to score at least 10 touchdowns now that Cousins is at the controls. 

Case Keenum Debut Shows Broncos Passing Offense a Work in Progress

Unfortunately for the Broncos, Keenum and his receivers resided on the opposite end of the chemistry spectrum. 

Suiting up against his former team, Denver's marquee free-agent signee came out and fired his first pass to Demaryius Thomas for a five-yard completion. 

And that was as good as things got.  

Keenum was on the field for a pair of three-and-outs, and he didn't complete another pass before his night was over. 

All told, he went 1-of-4 and averaged 1.3 yards per attempt before Paxton Lynch—who was disappointing in his own right—took over. 

But like anything else in the preseason, the "small sample size" caveat has to apply. 

"I'll be honest. I wanted one series with a [few] more plays and score a touchdown," Keenum told 9News' Rod Mackey, per 104.3 The Fan's Cecil Lammey. 

"This is a great test," he added. "[Minnesota] was one of the top defenses in the league last year so we knew we had our work cut out for us." 

Given Saturday's struggles, the Broncos should make a concerted effort to get Keenum in more of a rhythm with his top targets in Week 2 of the preseason against Chicago. 

Royce Freeman Shows Traits of Bell-Cow RB with Explosive TD 

The past few years, the Broncos have cycled through running backs in hopes of identifying a potential backfield cornerstone to no avail. 

If Royce Freeman has anything to say about it, those days will be over soon. 

The third-round pick made a strong first impression Saturday with four carries for 38 yards, and his 23-yard touchdown run in the second quarter showed decisiveness at the first level of the defense and explosiveness once he was able to climb into the open field:  

Remember, that's the same back head coach Vance Joseph said "absolutely" has a chance to win the starting job, according to ESPN.com's Jeff Legwold.  

It's also the player former Broncos running back Terrell Davis believes is in line to take over as Denver's lead dog based on the buzz that's emanated from the organization. 

"I've talked to people in Denver," Davis said on NFL Total Access, per Mile High Report's Tim Lynch, "and they're just thrilled by what they see in camp and what they saw in minicamp from Royce Freeman. They think he's going to be the starting running back."

Freeman still needs to stitch together encouraging carries in Weeks 2 and 3 of the preseason, but at this point, he appears to be in the driver's seat for the No. 1 job. 

What's Next? 

The Broncos will remain home for a showdown against the Chicago Bears on Saturday, Aug. 18. The Vikings will be in action the same day when they host the Jacksonville Jaguars at U.S. Bank Stadium.