ARLINGTON, Tex. — The Panthers' rush defense finally cracked.

And so did their pass rush.

And so did their offensive line.

And as a result of all those things happening at once, they lost for the first time this season.

The Panthers watched a 14-13 halftime lead evaporate, losing 36-28 to the Cowboys at AT&T Stadium.

Throughout its 3-0 start to the season, Carolina was able to count on the league's top-ranked defense, which was allowing just 45.0 rushing yards per game, and had collected 14 sacks.

Sunday, the Cowboys ran for 245 yards, and the Panthers failed to sack Dak Prescott.

Meanwhile, quarterback Sam Darnold took more of a beating than he had previously this season.

He was hit 11 times and sacked five times. And when he threw a couple of interceptions in the third quarter, the Cowboys capitalized quickly, and things began to get away from the Panthers.

Protection is an issue for them. That's not a new concern. When Darnold had Christian McCaffrey to dump the ball to quickly, they were able to cover up some of that.

Sunday, it was obviously an issue, and one they'll have to fix in a hurry.

But the bigger concern is the way a defense that had been so stout — and depended on their pressure to get to opposing quarterbacks — vanished.

— Panthers head coach Matt Rhule has leaned to the conservative with his field goal decisions, and may regret not being more so Sunday.

Right after halftime, he let Zane Gonzalez try a 54-yard field goal, which is near the edge of his range. When he missed it wide left (he had plenty of distance), the Cowboys took advantage of the field position boost for a four-play, 56-yard touchdown drive and a 20-14 lead. Dallas never looked back, outscoring the Panthers 20-0 in the third quarter.

Before Sunday, Rhule had been willing to punt and trust his defense.

Sunday, he went away from that tendency, and it didn't work.

— As the game got loose in the third quarter, it became increasingly clear that the Panthers were playing with a number of backups on defense, specifically in the secondary.

With cornerback Jaycee Horn and safety Juston Burris going on IR last week (joining nickel Myles Hartsfield there), the Panthers began to spring leaks.

Mostly, that's because Prescott is good enough to find the gaps in their coverage. He finished 14-of-22 for 188 yards while tying his career-high with four touchdowns.

For his second, Prescott found Amari Cooper for a 35-yard touchdown behind the coverage of new cornerback CJ Henderson, but that wasn't the fault of the recent trade acquisition as much as it was a great throw and catch.

But there also appeared to be some communication issues by the Panthers as the game progressed. Cornerback A.J. Bouye was making his season debut, and he and safety Sam Franklin Jr. let Cedrick Wilson pass between them unchecked for an easy touchdown late in the third quarter.

— Playing without McCaffrey, the Panthers knew they'd have to improvise on the ground.

They did just that in the first half, and Darnold did a lot of the work himself.

He rushed for two touchdowns, taking the league lead with five this season. It marked the most rushing touchdowns by a quarterback in the first four games of a season in the NFL's Super Bowl era.

They also got a reasonably solid day out of the rest of them, with Chuba Hubbard totaling 71 yards on 15 touches.

DJ Moore also ran for a fourth-down conversion in the third quarter, as they tried to mix it up.

— There will be complaints about the fumble that wasn't in the first half (Cowboys tight end Dalton Schultz was ruled down, with his forward progress stopped, as Jeremy Chinn was knocking the ball away). But even though the Panthers didn't get the call they wanted there, they still went into the half with a 14-13 lead.