The San Francisco 49ers dominated the Pittsburgh Steelers 30-7 in just one of the big wins of an NFL opening Sunday that ended with the Cowboys' 40-0 dismantling of the New York Giants.

The San Francisco 49ers, beaten in the NFC Championship game last season by the Eagles, got off to a perfect start against the Pittsburgh Steelers, where quarterback Brock Purdy threw for 220 yards and two touchdowns.

After grabbing the starting role in his rookie season, San Francisco's Purdy underwent elbow surgery during the off-season but showed no signs of any lingering issues as he completed 19 of 29 passes.

Running back Christian McCaffrey also enjoyed a dominant opening day as he rushed for 152 yards and a touchdown.

"We're here to win. This is how we're going to play," said Purdy, who connected on two touchdown passes to Brandon Aiyuk in the first half.

The Steelers trimmed the deficit late in the first half when Kenny Pickett capped a 12-play, 95-yard drive with a three-yard scoring pass to Pat Freiermuth.

But San Francisco's defense held firm in the second half and McCaffrey's magnificent 65-yard rushing touchdown in the third quarter crowned an excellent win.

It was a different story for last year's AFC runner-up Cincinnati Bengals as quarterback Burrow struggled against a dominant Cleveland Browns defense.

One day after signing a $275-million contract extension that makes him the league's highest-paid player, Burrow was held to a career-low 82 passing yards.

The Browns ultimately stifled the Bengals in a 24-3 victory.

"Obviously not very good today," said Burrow, who said his missed training because of a pre-season calf injury was perhaps a reason, but no excuse, for the sputtering performance.

Browns quarterback Deshaun Watson, who missed the first 11 games of last season after he was suspended following an investigation into sexual harassment allegations, threw one touchdown and ran for another as the Browns coped better with the rainy conditions.

It was also raining at the Meadowlands outside New York, where the Dallas Cowboys posted the most lopsided opening Sunday victory since the Steelers beat the Browns 43-0 in 1999.

Dallas quarterback Dak Prescott completed only 13 of 24 passes for 143 yards, but with 11:19 left in the fourth quarter, he was already watching from the sidelines.

The Cowboys had a special teams touchdown, a defensive touchdown, and three rushing touchdowns – including two by Tony Pollard.

The Dallas defense meanwhile held the New York Giants to 171 offensive yards, sacking Giants quarterback Daniel Jones seven times. They forced three turnovers – including DaRon Bland's interception and 22-yard return for a touchdown.

Prescott put the win down to "the discipline of our team – getting up early, staying committed to it, not getting ahead of ourselves."

The Philadelphia Eagles – beaten in last season's Super Bowl by the Kansas City Chiefs – held off the New England Patriots 25-20, while the Tampa Bay Buccaneers started life after Tom Brady with 20-17 victory against the Minnesota Vikings.

Miami Dolphins quarterback Tua Tagovailoa provided plenty of fireworks in a thrilling 36-34 win at the Los Angeles Chargers.

Tagovailoa threw a go-ahead four-yard touchdown pass to Tyreek Hill with 1:45 to play. The Dolphins defense then came up with two of their three sacks of Chargers quarterback Justin Herbert to seal the victory.

New Green Bay Packers quarterback Jordan Love, at the helm after the departure of four-time Most Valuable Player Aaron Rodgers, threw for 245 yards and three touchdowns in a convincing 38-20 win over the Chicago Bears.

On Monday, Rodgers makes his debut for the New York Jets against the Buffalo Bills.

It was close in Louisiana, where New Orleans Saints quarterback Derek Carr was sacked four times and threw an interception but kept alive a late drive that let the hosts claim a 16-15 victory over the Tennessee Titans.

The Las Vegas Raiders also won by the slimmest of margins, edging the Denver Broncos 17-16 to spoil Sean Payton's debut as coach.

The Baltimore Ravens shook off a slow start to beat the Houston Texans 25-9, but it was a bittersweet victory as running back J.K. Dobbins suffered a season-ending torn Achilles tendon.