Minneapolis — The Minnesota Vikings, still seeking to salvage a season that started with Super Bowl designs, made a last-ditch move to capture a mid-December spark by firing offensive coordinator John DeFilippo.

Coach Mike Zimmer made what he called an “extremely difficult decision” on Tuesday morning, following a 21-7 defeat at Seattle on Monday night . DeFilippo’s first season on the job ended after just 13 games, amid a sharp decline in production by the offense over the past six weeks.

“I went round and round and round and round about it because I feel like, ‘I hired him. It’s my job to try to help him to continue to get better,’” Zimmer said. “I obviously didn’t do a good enough job there. I’ve always felt like if you hire a guy, you should stick with him and try to help him and help him mature as a coach.”

The Vikings (6-6-1) have been held to under 300 total yards in four of their past five games. They’ve scored an average of 12.8 points in those four games. Thanks to the struggles of several of their NFC competitors, though, they’re still in control of the second wild-card spot with three games to go.

“I don’t want the season to be wasted. Now, maybe it will. Maybe it won’t,” Zimmer said. “But these three games, to me, are very, very critical.”

Quarterbacks coach Kevin Stefanski was made interim offensive coordinator, taking over the play-calling duty. Stefanski has been an assistant with the Vikings since 2006, surviving two head coaching changes . Having coached quarterbacks, running backs and tight ends under Zimmer, Stefanski has a firm grasp of the scheme and the personnel.

“We’ve got a lot of smart guys in that room, and I’ll try to help him best I can,” Zimmer said.

DeFilippo’s work with new quarterback Kirk Cousins (Michigan State) didn’t materialize into consistent success, but Zimmer said his reasoning for dismissing DeFilippo transcended Cousins and his so-so first year with the Vikings.

“This really wasn’t about one guy. This was about a lot of us holding up our end of the bargain. It was a collective thing,” Zimmer said.

Oakland sues NFL, Raiders

The city of Oakland filed a federal antitrust lawsuit trying to recover damages for the Raiders’ move to Las Vegas.

The suit filed Tuesday in U.S. District Court for the Northern District of California against the Raiders, the NFL and the other 31 clubs seeks lost revenue, money Oakland taxpayers invested in the Raiders and other costs.

The suit does not ask the court to prevent the Raiders’ move to Las Vegas but asks for damages that will help pay off the approximately $80 million in debt remaining from renovations on the Coliseum.

The city says the defendants violated federal antitrust laws and the league violated its own relocation policies when the teams voted in March 2017 to approve the Raiders’ decision to move to Las Vegas.

Extra points

The Bills placed starting linebacker Matt Milano and cornerback Taron Johnson on the season-ending injured reserve list.

Milano broke his fibula in the final minutes of a 27-23 loss to the New York Jets on Sunday.

Johnson had surgery last week for a shoulder injury.

The Bills, out of playoff contention with a 4-9 record, will host the Lions on Sunday.

... Steelers quarterback Ben Roethlisberger believes he’ll play on Sunday when New England visits Heinz Field.

Roethlisberger missing most of the second half in a loss against the Raiders after taking a shot to the ribs.

... The Rams placed running back Malcolm Brown and cornerback Dominique Hatfield on injured reserve.

Brown, Todd Gurley’s backup, injured his collarbone earlier this month. Hatfield will need surgery after injuring his ankle Sunday.