With the regular season approaching, Vikings offensive coordinator Norv Turner still sounds concerned about his offensive line.

“We have a lot of work to do in the offensive line and we don’t have a whole lot of time to get it done before the opener,” Turner said. There are reasons for concern.

Center John Sullivan has been out of action for nearly two weeks because of back spasms, which means the line has been without its leader. The Vikings lost right tackle Phil Loadholt for the season because of a torn Achilles’ in the second preseason game.

Since then, the Vikings have been trying to get a radically different offensive line to jell. Brandon Fusco is now at left guard. Mike Harris, last season’s backup swing tackle, is now at right guard. And rookie T.J. Clemmings has been made the starting right tackle.

The team is also thin with backup help. Carter Bykowski, a potential swing tackle candidate, has been waived, leaving Austin Shepherd and David Yankey to compete for that role.

Bykowski cleared waivers Tuesday and has officially reverted to injured reserve.

The good news is that left tackle Matt Kalil and Fusco have played well on the left side. But, while both Harris and Clemmings have progressed, both need to get much better by opening day, when opposing teams will begin scheming to take advantage of the line’s weaknesses.

“People are looking at you and looking at the things they can do to beat you,” Turner said. “There are challenges ahead for us.’’ Indeed. Turner said the team will need a little luck when it comes to the line, something that has been in short supply of late.

Big plays to come

In Dallas last week, fans finally got to see a long Teddy Bridgewater-to-Mike Wallace connection. With starters not expected to play much, if at all, in Thursday’s preseason finale, we’ll probably have to wait until the regular season before seeing that again.

That said, neither Turner nor Wallace is concerned about the lack of such plays in the preseason.

“If he was a guy who was a rookie, and he hadn’t made plays in games, you’d say, ‘We have to see more in games,’ ” Turner said. “He’s not in that category. He’s played a lot better in the last two years than people give him credit for. If we can get him to catch 65 balls and have 10 touchdowns or nine touchdowns, he’ll make a great contribution and help our team.’’

Wallace was acquired from Miami during the offseason to add a deep threat to a Vikings attack that will also have Adrian Peterson back.

But, so far, Wallace has been relatively quiet. “[My] specialty is deep balls, and everyone wants to see it,’’ Wallace said. “But we have other things to work on. We’ll get to that. I have complete confidence our coaching staff will have a great plan set up for us. It will come.’’

Reaching 75

The Vikings got down to the mandated 75 players by waiving quarterback Mike Kafka, who did not practice Monday, with an injured designation.

The move leaves the team with three QBs on the roster. With Bridgewater not expected to play and backup Shaun Hill possibly being held out, too, fans should see a lot of rookie Taylor Heinicke for much of the Titans game Thursday.

Etc.

• For a 13th consecutive day, Sullivan was sidelined because of back spasms. He has missed seven practices and two preseason games and will miss a third Thursday. Also not practicing Tuesday because of injury were tight end Chase Ford, defensive tackle Shamar Stephens and linebacker Brian Peters.

• Count Wallace among those who can hardly wait to see Peterson — who has been held out of the preseason — carry the ball come opening day.

“Of course I am,” he said. “Wouldn’t you be, if you were on this team? I never played with him. I’m excited. You watch him from afar and you know he’s a great player. I want to see him play [up close]. It’s going to be fun. There are some celebrations we’ll need to make up, for touchdowns.’’