If they walk out of Lambeau Field victorious, the Lions will climb to 4-1, have beaten all three of their NFC North rivals and drop the Packers to 1-3 in the process. If the Chicago Bears don't upset the red-hot New Orleans Saints, the Lions will be all alone in first place, with all of the crucial head-to-head and division-record tiebreakers in hand.
In other words, they'll be in the driver's seat.
There's just one small problem: The Lions haven't won in Wisconsin since Dec. 15, 1991.
For a little perspective, Brett Favre was a rookie on the Atlanta Falcons at the time. Jason Hanson was kicking at Washington State University. The mighty Lions went 12-4 that season and made the NFC Championship Game. The meek Packers went 4-12.
I was ten years old.
It's a given that Matthew Stafford and the Lions offense will throw the ball early and often; Stafford led the NFL in pass attempts in 2011, 2012 and currently ranks 10th this season, per Pro Football Reference.
It's a given that Calvin Johnson will play and play well—despite being listed as "questionable" on the Lions' official injury report— [Update: apparently not; ESPN's Adam Schefter reported on Twitter that Johnson will not play] and that Reggie Bush and Joique Bell will run hard and catch the ball well.
It's a given that the Lions offense will rack up some penalties and turnovers along with their 30.5 average points; these things happen no matter whom the Lions play.
Also a given: that Aaron Rodgers is the best player in the NFL.
Rodgers and the Packers are one of just three teams outscoring the Lions offense this season. Meanwhile, the volatile Lions defense has allowed 25 points to the Arizona Cardinals (who are averaging 17.2 per game)—but forced four turnovers while shutting down the Bears.
How much the Lions will be able to clamp down on Rodgers will swing the outcome of the game.
Almost but Not Quite
The Lions defense almost pulled it off last season.
They held the Packers offense below its 2012 average of 27.1 points per game in both divisional matchups. Making that more impressive: The Lions 27th-ranked defense allowed an average of 27.3 points in 2012.
I'll say it again: The Lions' 27th-ranked defense faced the Packers' fifth-ranked offense twice in 2012. In both games they held the Packers below their own points-allowed average and below the Packers' points-scored average.
Last season, the Lions nearly ended their streak of futility at Lambeau, drawing first blood and taking a 17-17 tie into the fourth quarter. Ultimately they lost 27-20, but the losing streak was in serious danger.
The Run Game
The Packers aren't known for their running game, but this season they're averaging 5.3 yards per carry, second best in the NFL. With starting rookie tailback Eddie Lacy ready to return from a concussion, the Lions will have to account for Green Bay's ground attack.
But, if they account for it too much, they will have no hope of slowing Rodgers.
Last season in Lambeau, the Packers tried to get their tailbacks outside with tosses and zone stretches. The Lions defense typically won these races to the edge, and runs inside were swallowed up by the Lions' defensive tackle tandem of Nick Fairley and Ndamukong Suh.
The Lions held the Packers run game to very little until the second half, when the Packers realized that right tackle Bryan Bulaga on Lions left end Willie Young was a physical, run-blocking mismatch. According to Pro Football Reference, Packers' running backs ran to either side of Bulaga (or directly behind him) 10 times for 76 of their 108 combined rushing yards.
This season, the Packers' offensive line has been heavily reshuffled. Bulaga was supposed to switch to left tackle but is out for the season with an ACL injury. Instead Don Barclay is starting at right tackle, and rookie David Bakhtiari is starting on the left side.
According to Pro Football Focus (subscription required), the new-look Packers line is run-blocking very well; it ranks fifth in the NFL as a unit. PFF has through three games given positive run-blocking and overall grades to Barclay, right guard T.J. Lang and center Evan Dietrich-Smith.
For the Lions, Young will again be going against the right side of the Packers line. He's getting the start in relief of the injured Jason Jones. PFF grades Young just on the positive side in run-stuffing so far this season (and No. 14 out of 50 defensive ends who qualify), but this matchup will be key.
If a receiver is open, Aaron Rodgers will find him. The key to slowing down Rodgers is making sure all his receivers are covered.
The Lions' mostly successful approach last season was to keep their defense surprisingly vanilla. With both safeties deep in a Cover 2, the Lions typically covered the Packers receivers with nickel personnel in off-man coverage, like this:
The off-man coverage puts a lot of cushion between the Lions' defensive backs and the Packers receivers, but that keeps the play in front of them. When the pass is short, as it is on this receiver screen to Randall Cobb...
...the Lions can flow downhill to the ball:
That play stopped the dangerous Cobb after a seven-yard gain on 3rd-and-15.
When the pass is deep, as it is on this attempt to Cobb...
...the Packers receivers all get ten yards downfield, but none are behind the Lions coverage. At this instant, the Packers offensive line has given Rodgers a little time, but nobody's open yet. Then, Suh splits his double-team:
With Suh bearing down on him, Rodgers is forced to roll to his right. Cobb breaks off his pattern and finds open space, and Rodgers launches it to Cobb just before Suh creams him. The Lions defensive backs converge on Cobb, forcing an incompletion despite an outstanding across-the-body throw by Rodgers:
This play perfectly illustrates the design of the Lions defense in general and their ideal game plan against the Packers: drop seven into coverage and take away the deep and intermediate routes, then rely on the front four to get pressure.
This play also illustrates the two main challenges the Lions face: avoidable penalties (Suh was flagged for roughing the passer) and Rodgers' athleticism. Rushing the passer with just four linemen is possible, but unless the defensive linemen consistently win their individual battles with the Packers OL, it's quite difficult. If the Lions add stunts or twists to their game plan to get more pressure, they will quickly lose containment.
If you don't think losing containment on Rodgers is a problem, the Lions surrendered the lead in Lambeau last year doing exactly that. Watch as the Lions drop seven into coverage, very nearly sack Rodgers and then helplessly watch as he squirms away and scampers for a 27-yard touchdown:
How can the Lions get pressure with four rushers without losing containment?
One tactic the Lions could try is switching to a more aggressive single-high look, with free safety Louis Delmas playing centerfield and the rest of the defensive backs playing tight man coverage, as they did against the Bears last week (Delmas intercepted Jay Cutler on this play):
This shuts down hot reads and short timing routes, allowing the Lions' pass rush to get upfield (or even blitz) without getting burned on quick passes.
Rodgers, however, is not Cutler and is more likely to pick apart this kind of aggressive coverage. Furthermore, the Packers like to spread the offense more than the Bears, putting even more pressure on the Lions' defensive backs to play at a high level until the rush hits home.
Worst of all, Detroit's best defensive back, cornerback Chris Houston, is hurt. Per Dave Birkett of the Detroit Free Press, the Lions are "optimistic" Houston will play, but it's hard to imagine he won't be slowed by his leg injury.
The Lions may want to borrow a trick Rob Ryan used last season as defensive coordinator of the Dallas Cowboys. From Ryan's 3-3-5 nickel, outside linebacker DeMarcus Ware set up on the line, creating a look very much like the 4-2-5 the Lions ran consistently last year against the Packers:
After firing off, defensive lineman Jason Hatcher pulls up and backpedals, spying Atlanta Falcons quarterback Matt Ryan:
With the great coverage downfield, Ryan held on to the ball until Ware nearly sacked him, forcing the QB to flee to his left. He might have scrambled for 10, 15 or 20 yards if Hatcher hadn't been spying; instead Ryan rolled toward the sideline and threw it away.
The Lions have actually dropped Suh back into a linebacker look before. Here's (admittedly poor) video of Suh blitzing from a standup look and sacking Tom Brady:
They shouldn't use this tactic on every play, but if the Lions want to stunt to get a pass-rusher free, they could drop Suh or Fairley back as a spy. Either would have had enough athleticism to prevent the 27-yard scramble that broke the Lions back last season.
The Turning Point
It's hard to overstate how big of an opportunity this game is for the Lions and what it could mean for their season. Breaking their 22-year road-losing streak against the Packers would be enormous, of course, and give the Lions a big mental advantage in the home rematch.
Should these two teams meet again in Lambeau in the postseason, having already slain this psychological dragon would be enormous for Detroit.
With a win, the Lions would put themselves two-and-a-half games ahead of the Packers and put for the time being the all-important tiebreakers on their side. They'd also have an unquestioned grip on the division—at worst, they'd be tied with the Bears (but, again, holding the tiebreakers).
It's also hard to overstate how big of an opportunity this would be to miss.
If the Lions can't slow down Aaron Rodgers, the Lions drop to 3-2, the Packers jump up to 2-2, with the Bears having a chance to claim first place in the division. The Lions would also lose all of that undefeated-in-division mojo.
This is where Jim Schwartz can earn his money. If ever there's been a time for he and defensive coordinator Gunther Cunningham to get creative and create a tactical advantage, this Week 5 in Green Bay is it.