On their first offensive snap Sunday in Dallas, the Cleveland Browns obliterated the Cowboys at the line of scrimmage so thoroughly no defender could even lay a hand on Nick Chubb until he'd almost reached the first-down marker. The 24-yard gain set the tone for the day and sent a message around the league.

This Browns' running game isn't just legit. It's a budding juggernaut.

Through four games, Cleveland tops the NFL with 818 rushing yards and averages a league-best 5.88 yards per carry. On top of that, the Browns have posted the fourth-highest total through any team's first four games to start a season over the past 30 years. Only the 2005 and 2006 Atlanta Falcons and last year's Baltimore Ravens rushed for more yards in their first four games -- and they boasted elite running quarterbacks in Michael Vick and Lamar Jackson, respectively.

Instead, the Browns are running roughshod over the opposition with smashmouth offensive line play, dogged perimeter blocking from their tight ends and wide receivers, and elite moves and tackle-breaking by Chubb and Kareem Hunt.

The Browns got some tough news Monday, when an MRI revealed Chubb had suffered an MCL injury to his right knee, which is expected to sideline him for several weeks.

Yet even after Chubb went down in the first quarter in Dallas, the Browns kept churning along on the ground. Hunt stepped in and ran for 71 yards and two touchdowns, and third-stringer D'Ernest Johnson barreled away for a game-high 95 yards. Together, Hunt and Johnson combined to average 7 yards per carry, and the Browns finished with 307 rushing yards, their highest game total in 11 years.

"That was good to see with those guys stepping up," said first-year coach and playcaller Kevin Stefanski, who has already implemented a clear and emphatic offensive identity in Cleveland. "The offensive line, the tight ends and the wide receivers, they are all straining, and the runners are running through arm tackles and breaking tackles.

"You lose a player of Nick's caliber, we are going to need those guys to step up, really across the entire offense."

Replacing Chubb, a Pro Bowler last season who entered the Dallas game fourth in the NFL in rushing, presents a considerable challenge for Stefanski and the Browns' offense. Even after missing most of Sunday's game, Chubb still ranks third with 148 rushing yards after contact. He's tied for second with four rushing touchdowns, and he's averaging a whopping 5.88 yards per carry.

But Sunday showed why the Browns might be equipped to weather the storm and keep rolling along until Chubb returns, which, according to ESPN's Adam Schefter, could be Nov. 15 against the winless Houston Texans.

One big reason for that is Hunt, who was the 2017 NFL rushing champ while with the Kansas City Chiefs. The other factor is perhaps the league's most improved offensive line, which is punishing opponents at the line of scrimmage.

Last year, a beleaguered Cleveland line ranked just 31st in run block win rate. This season, the Browns are second.

Free-agent signing Jack Conklin and first-round rookie Jedrick Wills Jr. have stabilized and solidified the tackle positions, which were a disaster last season. Inside, right guard Wyatt Teller has emerged into a run-blocking mauler, effectively flanking Pro Bowl left guard Joel Bitonio and veteran stalwart center JC Tretter.

Against the Cowboys, the Browns posted an 86.1% run block win rate, the highest percentage in a single game by any team since ESPN incorporated the metric using Next Gen Stats data before last season. Off that performance, the Browns now are one of only two teams to rank in the top five in both run block and pass block win rates (the Green Bay Packers, the other, played Monday night).

"It's easy to start with the runners who are doing an outstanding job, but you have to look at the entire offense and you have to look at the offensive line knocking guys off the ball, utilizing the correct technique and going to the right people," said Stefanski, who also credited experienced offensive line coach Bill Callahan for the staggering turnaround up front. "It really takes 11 guys to make a run game go."

It also helps to have a second elite back to bring in off the bench.

Hunt, who has five touchdowns, including three receiving, in his past three games actually ranks ahead of Chubb with 154 yards after contact, despite seven fewer carries. He leads the NFL with an average of 3.1 yards after contact per carry.

Hunt is more than capable of shouldering the load while Chubb is out. Especially if Johnson, one of the breakout standouts in training camp, can prove to be a reliable sidekick.

"I think we are pretty confident right now," Johnson said Monday. "It sucks that Nick had to get hurt. At the same time, we just have to continue to hold it down for the running back room."

The Browns face a pair of looming litmus tests these next two weeks. The Indianapolis Colts, next up on Sunday, boast the fourth-best run defense in the league; the Pittsburgh Steelers, who follow in Week 6, rank No. 1. The Cowboys, on the other hand, were just 23rd in run defense before the Browns decimated them.

"Nick is tough to replace obviously, but we have to just make sure we put a game plan together," Stefanski said, "and then find a way to move the rock any which way we can."

But so far, Cleveland has moved the rock on the ground at will. And as Sunday underscored, the Browns' rushing attack is about more than one player -- which is why it has been so tough to stop.