– Mike Zimmer has acknowledged that he probably won’t be able to fix the Vikings defense overnight. But in their third preseason game Saturday night, a 30-12 win over the Kansas City Chiefs, his starters showed flashes of the smothering unit he one day expects them to become.

“We get better and better each and every practice,” cornerback Captain Munnerlyn said. “We learn how to play with each other better. This defense, we can be one of the top defenses in the league.”

Sure, a cynic might say that is a little ambitious. They might also point out that the Chiefs were without star running back Jamaal Charles and top wide receiver Dwayne Bowe.

But for two quarters the Vikings harassed the first-stringers the Chiefs did trot out there, including quarterback Alex Smith, before Zimmer removed his defensive starters. And if not for some crafty scrambling by Smith, the Vikings might have doubled their total of five sacks.

“We probably could have made quite a few more if we were more disciplined in our rush lanes,” Zimmer said. “We had our hands around the quarterback quite a few times and didn’t get him on the ground.”

Zimmer probably wasn’t thrilled that Smith steered the Chiefs into the red zone three times in the first half, but the Vikings held them to just three points on those possessions. And after the Vikings took a 10-5 lead into halftime, they pulled away in the third quarter thanks to a pair of touchdown passes from rookie quarterback Teddy Bridgewater.

The Vikings improved to 3-0 in Zimmer’s first preseason as a head coach. In those three wins, the starters for the Vikings, who ranked next to last in total defense a season ago, surrendered just 17 points in about five quarters of action.

But they hadn’t, at least until Saturday night, pressured the quarterback with regularity. And they certainly hadn’t been forcing turnovers like they did against the Chiefs.

Munnerlyn intercepted Smith in the end zone in the first quarter, and in the second, linebacker Chad Greenway stepped in front of one of Smith’s passes in the red zone. Cornerback Shaun Prater got the Vikings’ third interception of the night — they had only one in their first two games — when he picked off Chiefs backup Tyler Bray after Smith exited early in the third quarter.

Offensively, Matt Cassel and the first-stringers picked up where they left off a week prior, when Cassel led the Vikings on three first-half scoring drives in a wild victory over the Arizona Cardinals.

After Chiefs punter Dustin Colquitt pinned the Vikings at their 3, Matt Asiata picked up 31 yards after catching a swing pass. Asiata moved the chains again with a couple of productive rushes. Then Cassel froze the Chiefs defense with a crafty play-action fake and fired a 53-yard touchdown pass to Cordarrelle Patterson for an early 7-0 lead.

But Cassel quickly cooled off, and linebacker Tamba Hali and a dangerous Chiefs pass rush had something to do with that. Cassel was sacked three times, including one in the end zone by Chiefs defensive end Jaye Howard that forced Cassel to fumble out of the back of the end zone for the safety.

In the second quarter, with the Vikings leading 7-5, Cassel made his first glaring mistake of the preseason, overshooting wide receiver Jerome Simpson on a deep ball. Chiefs cornerback Ron Parker picked off Cassel, the quarterback’s first interception of the preseason.

Cassel, who remained in the game until late in the third quarter and completed seven of his 15 attempts for 68 yards after the team’s opening drive, remains the heavy favorite to start Week 1.

Bridgewater entered the game after Prater’s interception and hit tight end Allen Reisner in the right flat for an 8-yard touchdown that expanded the lead to 20-5.

On the first play after a 75-yard punt return by wide receiver Adam Thielen, Bridgewater and Reisner connected again. The touchdown gave the Vikings a 27-5 lead and sent many of the sweaty stragglers left at Arrowhead Stadium, which had a temperature of 97 degrees at the opening kickoff, heading toward the parking lots.

Zimmer still has a lot of work to do on both sides of the ball before the season opener, including officially picking between Cassel and Bridgewater. But he appeared pleased with how far this team has come over the past few weeks, especially from a Vikings defense in transition.

“Obviously there’s still quite a bit of things we have to work on that we need to get better at,” Zimmer said. “But it’s good to see them get some interceptions. Usually when you get around the quarterback, good things happen.”