Since the Week 4 debacle in Los Angeles, the Vikings defense is nearing last year’s form, when it was the NFL’s top-ranked unit.

Most of the focus goes to the stingy 17.3 points per game given up in the past seven weeks, when the Vikings surrendered the league’s fewest passing touchdowns. But stopping the run — and particularly how — is what’s giving Mike Zimmer’s defense its old consistency.

The Vikings rank third in the NFL by allowing just 3.7 yards per carry despite playing with an additional defensive back instead of a third linebacker at least 70 percent of snaps — among the league’s highest rates.

While Sunday’s trip to New England conjures visions of 41-year-old quarterback Tom Brady throwing touchdowns, these Patriots are coming off a 215-yard rushing game against the Jets. They’ve leaned heavily on the backfield duo of Sony Michel and James White. So, the stingy nickel run defense will be tested.

“I think they’re going to try to run the ball on us,” Zimmer said Thursday of the Patriots, who are 5-0 at home this season.

Brady’s three top receivers — Chris Hogan, Julian Edelman and Josh Gordon — each average nearly 50 snaps per game. Most NFL offenses now start and end games playing three receivers, forcing defenses to play more defensive backs.

“Offenses are coming out in three-receiver sets on first down,” safety George Iloka said. “Pretty much carrying that for 80 percent of the game. So, you’re forced to go nickel on first, second and third down. Then they’re like, ‘Oh shoot, if you’re going to keep your nickel on first down, we’re going to try to run it down your throat.’ ”

The Vikings counter well.

When offenses spread out and run at the edges, fewer defenses are better than the Vikings. The physical play of cornerbacks and defensive ends has manifested in just 3.6 yards per run to the right edge (fourth in the NFL) and 4.7 yards to the left edge (sixth).

“We’re just mindful of stopping the run, whether we’re in nickel or base,” safety Harrison Smith said.

Smith is one of the best run-stopping safeties in the league, making him a valuable wild card for Zimmer to move into the box as an extra defender when the Vikings remove a linebacker.

The Vikings also added a new wrinkle this season with the “big nickel” package featuring safety Jayron Kearse as a slot defender, giving the nickel defense even more punch.

Kearse has responded with five run stops, second most in the Vikings secondary behind Smith, according to Pro Football Focus.

“There’s a real fine line,” Zimmer said. “Because usually when you go into nickel, guys are pass rushing. We don’t do that.”

Zimmer prides his defense on disciplined reads of possible runs before rushing the passer. Perhaps that’s why teams — such as the 49ers, Bills and Rams earlier this season — found success faking a handoff and throwing deep. Like those teams, the Patriots set up Brady’s passes through the run game.

New England is “the best play-action team in the NFL,” according to Zimmer, so the Vikings defense is preparing to walk that “fine line” between pouncing on the run and respecting Brady’s arm. Only three quarterbacks — the Rams’ Jared Goff, Chiefs’ Patrick Mahomes and Falcons’ Matt Ryan — have thrown for more play-action yards than Brady this season, per PFF.

Whether the Vikings defense is successful depends on nuanced decisions by Zimmer, who can wave off his respect-the-run-first mantra on any given play.

“Some plays he’ll tell us ‘OK, go,’ ” defensive end Danielle Hunter said. “He decides when to let us go eat.”

Sunday’s rushing totals will determine which team feasts.

The Vikings are 0-4 this season when allowing 100 or more yards on the ground, and the Patriots are 6-0 when running for the century mark.