There’s something intensely satisfying about the “we’re going to run at you, you know it, so try to stop us” attitude the Dallas Cowboys have brought to their opponents this year. And it’s been fun as hell to watch rookie Ezekiel Elliott run through, around, and all over defenses at a pace we haven’t seen in a generation.

Dallas travels to Green Bay this Sunday, where the Packers are on a historic tear of their own: Through four games, Dom Capers’s crew has the best run defense of the NFL’s modern era. It might be the least sexy aspect of football, but the 11 players who will be responsible for bottling up the run deserve some time in the limelight.

This Cowboys-Packers tilt is a classic unstoppable-force-meets-immovable-object matchup. It may have taken a few weeks to get up to speed, but the Cowboys’ league-leading rushing attack now looks like a runaway train. And Green Bay’s stout front could be the group that derails it.

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In their first four games, the Packers have allowed just 42.8 rush yards per game (first in the NFL), 2.0 yards per attempt (first), and just one rushing touchdown (tied for second). They’re one of two teams (along with the Vikings) that has yet to surrender a run of more than 20 yards (their longest being 14 yards). They lead the league in the percentage of runs that are stuffed at or before the line of scrimmage, per Football Outsiders. In other words, this run defense is absurdly good.

It all starts in the middle. Defensive tackles Mike Daniels, Kenny Clark, and Letroy Guion have provided incredible ballast for Green Bay’s run defense. Their ability to absorb punishment was apparent in Green Bay’s Week 3 matchup with the Lions. On these two plays — the first coming in the first quarter, the second in the third quarter; both 1-yard runs by Theo Riddick — Clark and Daniels ate up double-team blocks by Detroit offensive linemen. On both, Green Bay’s interior linemen held their ground, providing the leverage that the Packers’ edge players and inside linebackers needed to pursue and tackle the ball carrier.

Against the Giants last week, it was much of the same. In the three plays shown below, Daniels absorbs double- and triple-team attempts by New York and gives little ground on any of them.

Green Bay’s interior linemen aren’t just there to take on double-teams. Sometimes, they create havoc in the backfield themselves. Against the Vikings in Week 2, both Daniels and Guion beat the blockers in front of them before bringing down running back Adrian Peterson.

The run game is all about math. More likely than not, the offense will start off with a numbers disadvantage. As soon as a typical pocket-passing quarterback hands the ball off, he is no longer a part of the play, which gives the defensive players an 11-to-10 edge in bodies over the offense. Dak Prescott’s ability to run for the Cowboys neutralizes that advantage. That’s where Daniels, Clark, and Guion swing the numbers advantage back to the defense. These war daddies keep the linebackers behind them “clean” because their interior linebackers are able to avoid getting blocked or sealed. Green Bay’s gap integrity in the run game has been both consistent and reliable.

Against the Vikings in Week 2, the double-teams that Daniels and Clark took on up front enabled linebacker Joe Thomas to keep his eyes in the backfield, track the runner, pursue him, and make the tackle. All of that would’ve been a lot harder if he had a big 320-pound lineman moving downfield to seal him from the play. Daniels’s work up front was the catalyst that allowed Thomas to move freely toward the ball.

When Orleans Darkwa lost a yard on this play early in the third quarter of Green Bay’s game against the Giants last week, it was the interior defensive line’s ability to stop blockers in their tracks that caused New York’s entire offensive line to stack up into one big mess of bodies. As New York’s blocks fell apart, linebacker Jake Ryan easily set the edge and, along with Daniels and Guion, made the tackle.

Of course, none of this would work if Green Bay’s edge defenders weren’t consistently forcing runs into the meat of their defense. The Packers’ outside linebackers have been extremely disruptive against the run: Nick Perry, Julius Peppers, Clay Matthews, Datone Jones, and Kyler Fackrell set the edge, get off blocks, get into the backfield, and stuff anything that opposing offenses try to bounce outside.

Perry, who signed a one-year, $5 million contract over the offseason, has been living in the backfield this year, with five tackles for a loss to go with his 4.5 sacks. Late in the first quarter against the Lions, he snuck past an Eric Ebron block to blow up a Riddick run for a loss of 3.

Peppers, more known for his chops as a pass rusher, has gotten in on the fun as well. At 283 pounds, he’s a beast to block for tight ends on the edge, and when Detroit decided to run his way, things didn’t go so well. Peppers took rookie tight end Cole Wick to school, tackling Riddick for a loss of 6.

Run defense is a true team effort. Capers gets his defensive backs involved, whether it’s on corner blitzes or by playing Morgan Burnett or Ha Ha Clinton-Dix up near the line of scrimmage. Cornerbacks have to tackle when run plays get to the outside. At every level, the Packers have gotten production. And they’ve needed it. The first half of the Lions game notwithstanding, Aaron Rodgers and the Green Bay offense are a shell of the powerhouse we’ve seen over the years. Winning this tough NFC matchup with the Cowboys will come down to what happens in the trenches.

Capers and his run defense will set out to make Dallas one-dimensional on offense. They want to take the ball out of Elliott’s hands and task their other star rookie with carrying the load. Prescott has been extraordinarily efficient managing the game for Dallas while Tony Romo rehabs his back injury, but he’s still relatively limited as a passer and has thrown just four touchdowns on the season.

On Sunday, we’ll see the mythological battle of Hector vs. Achilles reenacted on the football field. We all know how that played out the first time, but while Elliott and the Cowboys’ run game look invincible, if Green Bay can get to their heel and collapse their rushing attack, the Cowboys start to look pretty mortal. It comes down to the Cowboys’ offensive line against the Packers’ elite, run-stuffing front. Whoever controls the line of scrimmage controls the outcome of the game.