For the first time in seven seasons as Vikings coach, Mike Zimmer had an offense in 2020 that was better than his defense.

Zimmer called last year’s defense the “worst one” he ever has had. But while the Vikings, en route to going 7-9, finished 27th in the NFL in total defense, they were No. 4 in total offense. That was their highest ranking in 16 years.

But Minnesota this season could go back to being better on defense than offense. The Vikings got several top players back on defense who missed time last year, and they brought in several notable free agents. And the offense could end up regressing.

Yes, the Vikings still have key weapons in running back Dalvin Cook and wide receivers Justin Jefferson and Adam Thielen, and quarterback Kirk Cousins is coming off a season in which he had a career-high 35 touchdown passes. But the Vikings have an unproven new offensive coordinator in Klint Kubiak, the offensive line looks weaker than last year, tight end Irv Smith Jr. is likely out for the season with a knee injury, and there are issues about who will be the No. 3 receiver.

During the preseason, Cook (rested) and Jefferson (shoulder) didn’t play, and Thielen (thigh bruise) got in for just four snaps. Without those players, the Vikings could do little on offense, with the first team producing just a field goal in six possessions in two games.

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So does Zimmer have any concerns about how the offense looked in exhibitions entering Sunday’s regular-season opener at Cincinnati?

“We didn’t play that much,’’ he said Monday. “I don’t know. We will just have to see.’’

On the offensive line, the Vikings last March released left Riley Reiff in a salary-related move, and he signed with Bengals. Reiff will line up Sunday at right tackle.

First-round pick Christian Darrisaw was supposed to be Reiff’s replacement, but he has been hampered by a groin injury and is expected to do some individual work in practice Wednesday for the first time in nearly a month. With Darrisaw not ready, Rashod Hill, mostly a career backup, has taken over at left tackle. The Vikings also have a new starter in right guard Oli Udoh, who was a tackle his first two seasons and barely played.

“I think it’s a little bit (of) unknowns, but I don’t’ think it’s a major concern,’’ Zimmer said about the line. “We’ll just have to find out if (the Bengals have) got some good rushers.’’

At tight end, the Vikings lost Smith after having released Kyle Rudolph last March in another salary-related move. To help fill the void, the Vikings acquired tight Chris Herndon in a trade last week from the New York Jets. But he won’t practice for the first time with Minnesota until Wednesday.

Smith, hurt in the Aug. 27 preseason finale at Kansas City, was the third Cousins target to go down since the start of training camp. The Vikings also have lost wide receivers Bisi Johnson (torn anterior cruciate ligament) and Chad Beebe (foot) for the season due to injuries.

Now, defenses might be paying even more attention to Thielen and Jefferson.

“It’s obviously difficult not having Irv,’’ Thielen said. “He’s such a dynamic player. … But we have a lot of options to help try to make up for that. It’s going to be all hands on deck.”

Competing to be the third wide receiver are Dede Westbrook, K.J. Osborn and Ihmir Smith-Marsette. But Westbrook, who caught 66 passes in both 2018 and 2019 for Jacksonville, has been slow in recovering from a torn ACL suffered last October and didn’t play in the preseason. And neither Osborn, a second-year man, nor Smith-Marsette, a rookie, has a career regular-season catch.

But the good news for the Vikings is Cook, Jefferson and Thielen all will be in uniform Sunday.

“It’s always great when you have all your weapons out there, guys who you know are going to make plays,” Hill said.

Hill doesn’t think there will be any adjustment period needed when they return, and Thielen agreed. He said Zimmer did a good job getting those who didn’t play or played little in the preseason ready in practices, which included having scrimmages.

“Would you like to be out there and getting some plays in the preseason?” Thielen said. “Yeah. But at the end of the day, you just go out there in Week 1 ready to go, and that’s what practice is for.’’

And at least there might be one other good thing Sunday for the Vikings’ offense. Cincinnati’s defense last season was almost as bad as Minnesota’s, ranking No. 26.