LAS VEGAS — Before there can be good times in this new era of Miami Dolphins football, there will be hardships.

The Dolphins’ season opener against the Las Vegas Raiders, in the debut of the new regime of general manager Jon-Eric Sullivan, coach Jeff Hafley and quarterback Malik Willis, proved as much. The Raiders rolled to a 27-13 win Sunday at Allegiant Stadium.

Miami starts 0-1 with the loss to an opponent which had the worst record in the NFL last season, resulting in the top pick in the past draft. The defeat offers a feeling of what many expected entering the season, that it will be a long year for the Dolphins.

“No one’s sitting in there feeling good right now, and I’m certainly not feeling good right now,” Dolphins coach Jeff Hafley said. “I am proud of the way the guys fought. … The fight, the fight was there.”

The Dolphins defense failed to contain second-year running back Ashton Jeanty, who rushed for 102 yards while scoring twice through the air on six receptions for 45 yards.

Veteran quarterback Kirk Cousins completed 21 of 30 passes for 160 yards and three touchdowns but was intercepted twice. He rarely faced pressure from the Dolphins pass rush.

Willis’ first start for the Dolphins saw him go 15 of 27 for 220 yards with a rushing touchdown and an interception.

“I think it could be way cleaner,” Willis said. “You never want to go out and lose a game, obviously not the first one, but we can’t let it dictate our whole season. Obviously, if seasons were meant to be dictated by one game, they’d call it the playoffs.”

As he was sacked five times, some — not all — were on him holding on to the ball too long. Willis went over the top with accountability after the game in accepting responsibility for all of them.

Rookie wide receiver Caleb Douglas had a big debut, with five catches for 94 yards, but running back De’Von Achane was held to 36 yards on 11 attempts.

Trailing, 17-6, at halftime, the Dolphins got a spark early in the second half when rookie safety Michael Taaffe intercepted an overthrown pass by Cousins over the middle that led to a touchdown.

Willis scrambled 14 yards down an open right side to find the end zone for Miami’s first touchdown of the season.

But the momentum of drawing within four, at 17-13, was short-lived. The Raiders started at midfield off one of several solid special teams returns on the ensuing kickoff. Las Vegas marched down the field, and Jeanty scored his second touchdown as linebacker Jacob Rodriguez got tripped up in coverage over Raiders fullback Connor Heyward on the ground near the line of scrimmage. Fellow Dolphins linebacker Jordyn Brooks couldn’t get to Jeanty in time to prevent him from reaching the goal line.

“They’re good. They’re really physical. They know what they like to do and they do it well,” said Rodriguez, who led Miami with 14 tackles, on failing to stop Jeanty on the ground. “A lot of it was self-inflicted. We got to set the edge, play with good pad level, just basic football.”

Two plays from scrimmage later, Willis threw an interception targeting Douglas deep. Raiders safety Treydan Stukes was there waiting for the pick, which Willis attributed to not stepping into his throw. The Raiders added a field goal off the following drive, which consumed 7:07.

With Miami down, 27-13, backup running back Jaylen Wright’s 79-yard kick return quickly got the Dolphins in the red zone, but kicker Riley Patterson shanked a field goal attempt wide left.

Another Dolphins drive later was ended with a third-down sack by defensive end Maxx Crosby, who beat Miami left tackle Patrick Paul. Paul called Crosby a “hothead” this past week in saying Dolphins would have to get under his skin and get him off his game.

An interception for safety Dante Trader Jr. early in the fourth quarter also didn’t amount to anything for the Miami offense, as another drive was halted by a sack. Later, it was a fourth-down incompletion needing 12 yards that ended another try to inch closer. In the end, it was wide receiver Malik Washington losing a fumble to seal it.

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The Raiders started the scoring Sunday as Cousins found wide receiver Jack Bech over the middle for a 15-yard touchdown pass in the first quarter to cap a 16-play, 93-yard drive that took a whopping 8:58 off the clock. Bech beat cornerback Chris Johnson running across the field and safety Zayne Anderson may have been responsible for help.

Miami appeared to stop Las Vegas for a turnover on downs on a fourth-and-1 before the score, but video review of fullback Connor Heyward taking a sneak on the direct snap had officials overturn the call and bring the Raiders offense back onto the field.

Las Vegas went up, 10-0, adding a field goal in the second quarter a play after it appeared starting safeties Taaffe and Anderson combined for a turnover. Taaffe punched the ball out on tight end Michael Mayer and Anderson recovered, but replay overturned the fumble as Mayer was down.

It was the second time Miami thought it escaped that series, as cornerback JuJu Brents’ taunting penalty negated a third-down stop on a pass breakup by Anderson.

“They just told me they called him for taunting,” Hafley said of the conversation with officials. “That’s something that we’ve emphasized. You can’t taunt. If it was indeed taunting, he’s going to get fined for it. You can’t do it.”

Later in the first half, the Raiders went up, 17-3, as Jeanty came out of the backfield and beat Johnson with a move to the inside for a 13-yard touchdown reception. The throw was Cousins’ 300th career touchdown pass.

“I really just got to clean up some of my technique,” Johnson said. “I feel like I was responsible for a few touchdowns, but at the end of the day, I just got to be cleaner in coverage.”

The Dolphins’ opening drive saw them pick up a pair of first downs, one with Willis scrambling and another with him throwing a back-shoulder completion to Achane down the left sideline, which he caught through contact from Stukes. The series stalled as Miami took a delay-of-game penalty facing the loud Allegiant Stadium environment on third-and-10 and couldn’t convert afterward.

The Dolphins had a pair of Patterson field goals in the first half and went into halftime trailing, 17-6.

The first one came thanks to a 25-yard completion from Willis to Douglas on second-and-26 after back-to-back holding penalties against Paul and center Aaron Brewer. Miami finished with eight penalties for 61 yards.

The second field goal came before halftime, as Willis threw a 30-yard strike to Douglas to set up a 37-yarder before intermission.

The Dolphins stay out west for the week of practice ahead of next Sunday’s visit to Santa Clara, California to play the San Francisco 49ers.