The uniforms have the same basic purple, yellow and white scheme that the Detroit Lions have seen from a team that has bedeviled them as much as any other over the years, but the Minnesota Vikings have changed their style if not their colors at the start of this season.

The Vikings are gobbling up yards on offense the same way they made their image over the years with the renowned Purple People Eaters defense that chewed up enemy offenses and quarterbacks.

A formidable challenge awaits the Lions in facing an energized Minnesota offense to go with a talented defense in Sunday's road game at U.S. Bank Stadium.

As Vikings head coach Mike Zimmer cautioned in his conference-call interview with the Detroit media on Wednesday, it's too early to make set-in-stone conclusions after three games. But having an offense ranked second overall is a new experience – even for Zimmer. 

"I'm not used to it, either," Zimmer said. "I'm glad it is."

Key additions on offense have paid off. Among them are former Lion Riley Reiff, signed as a free agent to play left tackle in an offensive-line upgrade, and running back Dalvin Cook, a second-round draft pick.

"They've got a great thing going right now," said Lions head coach Jim Caldwell.

Although the overall stats don't show it – except for being ranked third at stopping the run – quarterback Matthew Stafford expects another tough game from the Vikings' defense.

"Not a whole lot of blown assignments on film," he said. "They're in the right place at the right time. They know how to make in-game, in-play adjustments. They play fast and physical. Everything you'd want out of a defense, they do."

Here's how the Vikings shape up:

How the Vikings got to 2-1: Their two wins have been at home -- 29-19 over the Saints in Game 1 and 26-9 over the Buccaneers in Game 3. They lost to the Steelers, 26-9, in Game 2.

They had a 16-6 lead at halftime over the Saints and widened it to 29-12 for a comfortable victory. They had a 28-3 lead early in the third quarter and coasted home to beat the Bucs. The Steelers jumped to a 14-0 lead and never trailed.

QB shuffle, repeat: For the second straight season the Vikings have responded well to an early quarterback change. This year the switch was from Sam Bradford to Case Keenum after one game because of a knee injury to Bradford.

Last year Teddy Bridgewater sustained a career-threatening knee injury before the start of the season. The Vikings traded for Bradford and went 5-0, with veteran backup Shaun Hill starting the opener, then turning the offense over to Bradford for the rest of the season.

"They've been through it before," Zimmer said of the switch. "One of them said, 'We've done this before. It's not a big deal."

Bradford did not practice Wednesday, but Zimmer said he had not made up his mind on a starter for Sunday. Keenum has completed 64 percent of his passes with three touchdowns and no interceptions.

Offense, blocking out: Five of the nine offensive linemen were not on the roster last year, and three of them are starters. Reiff was signed early in free agency.

"Riley has played really well," Zimmer said. "We thought he was the best one out there."

Adam Thielen (19 catches, 299 yards) and Stefon Diggs (17 catches, 293) rank second and third respectively in the league in receiving yards. Diggs leads the league with four TD catches.

Cook provides a running-receiving dimension that the Vikings lacked last year. Cook is second in the league in rushing yards (288), and also second with four runs of 20 yards or longer. He also has proven to be a good receiver out of the backfield and solid in pass protection.

Defense: If the focus on the offense has cast the defense in a supporting role, it's a strong role with proven players. 

Tackle Linval Joseph, edge rusher Everson Griffen, linebacker Anthony Barr, safety Harrison Smith and cornerback Xavier Rhodes all have made the Pro Bowl.

They've been especially effective against the run so far, earning their No. 3 ranking by allowing an average of 62.7 yards per game.

They're also third in average gain per carry (3.0), and they haven't given up a rushing touchdown or a run of 20 yards or longer. The long run against them is 11 yards.

Special teams: Kai Forbath is 21 for 21 on field goals since being signed by the Vikings after nine games last year to replace Blair Walsh.

Forbath has been considerably less than perfect on extra points, though. He's missed 3 of 14.