Los Angeles (AFP) - New England's star Tom Brady quickly shook off the rust in his season debut, while the Denver Broncos discovered just how much quarterback Trevor Siemian means to them in their first loss on Sunday.
Brady returned to the NFL in vintage style, passing for three touchdowns in the Patriots's 33-13 drubbing of the Browns in Cleveland.
Brady, playing for the first time this season after serving his four-game "Deflategate" suspension, threw for 406 yards, connecting with tight end Martellus Bennett on three touchdown passes.
"It's been a fun week to get ready to play and be back doing what I love to do. I'm just proud of the way our guys played," said Brady after his sparkling season debut.
"We were close to breaking a few runs there, but 4-1 is a great place to be right now."
The Patriots, who won three of four with Brady absent, improved to 4-1 while the Browns, the only winless team remaining, fell to 0-5.
Even worse, Cleveland saw yet another quarterback go down to injury.
Cody Kessler, the third quarterback to start for the Browns this season, was knocked out of the game with chest and rib injuries late in the first quarter when he was drilled by Patriots linebacker Dont'a Hightower.
Robert Griffin suffered a broken bone in his left shoulder in the season opener and Josh McCown suffered a broken collarbone in the next game for the Browns.
A week on from their humbling 16-0 loss to the Buffalo Bills, the Patriots came out firing.
On their first possession they moved the ball 80 yards on eight plays, aided by three runs from LaGarrette Blount that included a one-yard touchdown sprint.
The Browns pulled level on their next possession, but the Pats responded with a drive capped by Brady's first touchdown pass to Bennett.
"I think it was a good win today," Brady said. "I thought the team played really well. It was fun to be part of it."
In Denver, Colorado, quarterback Matt Ryan engineered five scoring plays as the Atlanta Falcons handed Denver their first loss of the season with a 23-16 win.
- Kubiak to hospital -
Broncos coach Gary Kubiak said they couldn't contain the Falcons' strong running game.
"They spread us out," said Kubiak, who was admitted to a local hospital as a precautionary measure about an hour after the game because of flu-like symptoms.
"For their backs to own the field the way they did. It was a very good job on their part."
The Falcons won their fourth straight game as Ryan picked holes in Denver's vaunted defence and the Broncos offence sputtered without injured quarterback Siemian.
Siemian, who missed the contest with a left shoulder injury, was replaced by Paxton Lynch. The rookie quarterback completed 23-of-35 passes for 223 yards and a touchdown.
He tossed one interception and was constantly harassed by Falcons linebacker Vic Beasley, who had 3 1/2 sacks.
Atlanta kept the Broncos out of the end zone until Demaryius Thomas caught a three-yard touchdown pass from Lynch with 2:38 remaining.
In other games, the Minnesota Vikings improved to 5-0, seizing an early lead and playing stifling defence in a 31-13 victory over the Houston Texans in Minneapolis.
The Vikings led 24-0 in the second quarter, scoring on three of their first four drives. Vikings quarterback Sam Bradford completed 22-of-30 passes for 271 yards, two touchdowns and no interceptions. In four games with Minnesota he has yet to turn the ball over.
In Detroit, Matt Prater kicked a 29-yard field goal with 1:28 remaining as the Lions, who gave away a 14-point lead, rallied to hand the Philadelphia Eagles their first defeat of the season, 24-23.
Pittsburgh quarterback Ben Roethlisberger notched a Steelers milestone as his four touchdown passes in a 31-13 victory over the New York Jets took him to 15 through five games -- a club best.