SANTA CLARA, Calif. -- Richard Sherman has a strong message for anyone still doubting the unbeaten San Francisco 49ers.
"Don't flip-flop," Sherman said after the 49ers thumped the Cleveland Browns 31-3 on Monday night. "If you said we weren't going to make it, you said we were some way early on, stick with that position. Hold it. Don't try to give us credit now. At least stick by your word because I want you to sound like an idiot at the end. We know what we have in the building."
What the 49ers have is their best start since Joe Montana was throwing touchdowns to Jerry Rice.
But it wasn't the passing game that carried San Francisco past Cleveland. A steady, pounding running game and a dominant defensive effort did the trick this time.
Matt Breida ran 83 yards for a touchdown on San Francisco's first play from scrimmage, Baker Mayfield was harassed into his worst game as a pro, and the 49ers stayed unbeaten for their best start in nearly 30 years.
Even then, there were some questioning San Francisco's legitimacy.
"I feel like they're going to say that all year about us," said Breida, who had 114 yards on 11 carries. "I don't think anyone expected us to be 4-0 this year, to be honest. Probably expected us to be 0-4. They can say whatever they want. All that matters is who's in this locker room."
Tevin Coleman added a 19-yard score as part of a dominant ground game on a day when quarterback Jimmy Garoppolo passed for 181 yards and kicker Robbie Gould missed a pair of field goal attempts and had a third try blocked.
San Francisco (4-0) joined the 5-0 New England Patriots as the only remaining undefeated teams in the NFL. It's the first time the 49ers have won their first four games since 1990.
"It's a good start is really all it is," Garoppolo said. "We have a good mindset in that locker room."
The Browns (2-3) are headed the opposite direction after losing two of three, with fresh concerns about their young quarterback.
"You can't have mistakes. You can't have turnovers. You can't have drops. You can't have penalties," Cleveland coach Freddie Kitchens said. "Offensively, that kind of summed us up. We just shot ourselves in the foot too many times."
Mayfield had a horrible game. The No. 1 overall pick last year, Mayfiaeld completed 8 of 22 passes for a career-low 100 yards, had a 13.4 passer rating, threw two interceptions, fumbled twice and was sacked four times before being pulled in the fourth quarter.
It's the first time in Mayfield's 18 career starts that he failed to throw a touchdown pass.
"It was like one step forward, two back," Mayfield said. "No rhythm for the offense to get into. And when we did, we just got down in the red zone and didn't finish. The inconsistency is killing us right now."
Things were rough all around for Mayfield.
San Francisco defensive end Nick Bosa poked fun at the Browns quarterback after forcing Mayfield into a hurried incompletion in the second quarter. Bosa, the second overall draft pick, got up and pretended to wave a flag and plant it in the turf as the crowd roared. It was a clear shot at Mayfield, who planted an Oklahoma flag in the turf after leading the Sooners to win over Bosa and Ohio State in 2017.
"I think everybody knows what that was for," Bosa said. "Just wanted to get payback. He had it coming."
San Francisco forced four turnovers overall.
The 49ers were coming off a bye and had two weeks to prepare, while the Browns flew cross country.
Breida raced past the Browns' front line and went untouched on his long touchdown run, waving to safety Demarious Randall as he sprinted into the end zone with the 49ers longest run of the season.
Fans at Levi's Stadium barely settled back into their seats when Sherman picked off Mayfield near midfield, setting a rough tone for Cleveland's second-year quarterback.
Breida and Coleman combined for 211 rushing yards as San Francisco outgained Cleveland 275-102 on the ground.
"It's something you always want to do as a coach," 49ers coach Kyle Shanahan said. "It's the easiest way to win. You play real good defense and you can run the ball, that takes some pressure off a lot of people and doesn't put you in a lot of risky situations."
That took pressure off Garoppolo, who passed for two touchdowns and completed 20 of 29 throws.
Garoppolo's 5-yard throw to Breida put the 49ers up 14-0 early in the first quarter. He later connected on a 22-yard pass to tight end George Kittle in the third that made it 28-3.
NOT THIS TIME EITHER
The 49ers' defense is the only NFL team to not allow a rushing touchdown this season. Browns running back Nick Chubb had 87 yards on 16 carries but was a non-factor for most of the game, especially after Cleveland fell behind big.
BECKHAM OR BAKER
Browns wide receiver Odell Beckham Jr. threw a 20-yard completion to Jarvis Landry on Cleveland's first play. Beckham took a handoff from Mayfield for what initially looked like an end around before reversing direction then pulling up to pass. It's the third time in his career that Beckham has completed a pass, but the first time this season.
Beckham was upset he didn't get the ball to Antonio Callaway, who was open deep.
"We made eye contact and I could not throw it to him," Beckham said. "There might have been an opportunity to throw it deep and it could have changed the whole momentum of the game."
49ers: Fullback Kyle Juszczyk left the game with a sprained left knee midway through the third quarter. Juszczyk, who had a pivotal block on Breida's long touchdown run, wore a thick black brace on his leg while walking through the locker room after the game.
Browns: Return to Cleveland to host Seattle on Sunday before getting a week off for the bye.
49ers: Play at the Los Angeles Rams on Sunday in a key divisional matchup for both teams.
More AP NFL: https://apnews.com/NFL and https://twitter.com/AP—NFL