Baker Mayfield has never felt this confident heading into the first game of a regular season.

He's certainly never lacked confidence before. Mayfield, entering his fourth season as Browns quarterback, has always been fueled with an underdog mentality to maximize determination in himself and his teammates. It's how he reached the NFL after he walked on at Texas Tech and became a Heisman-winning quarterback worthy of a first overall pick in 2018, and it's how he's helped turn the Browns franchise into one of the most promising teams in the league.

But this season, Mayfield's belief he can help the Browns meet their high 2021 expectations is at a new level. He showed it through training camp with how well he passed the ball and commanded the huddle, and he spoke about it again Wednesday as the Browns prepare for their Week 1 heavyweight battle against the Kansas City Chiefs.

"We have the bread and butter, the fundamentals and the schemes we know we're good at," Mayfield said Wednesday. "We need to keep building off those and do them extremely well."

The Browns have plenty of reasons to believe that will happen. 

Mayfield and head coach Kevin Stefanski spoke at length during camp about their comfort with the playbook and working together for a second consecutive season, something Mayfield has never been able to do with an NFL coach. The days of learning the playbook ended long ago for Mayfield, and that's put him in position to critique his teammates and feel even more comfortable in the pocket as he progresses through his reads.

Then, there's the chemistry factor. 

When Mayfield enters the huddle with the offense for the first time Sunday at Arrowhead Stadium, he'll be surrounded by the same players who joined him in that huddle for the first game a year ago. The top playmakers of the group are a close-knit bunch — as evidenced by the mini-vacation Mayfield took with some of his receivers last weekend — and ready for the challenge presented by the Chiefs, who knocked the Browns out of the playoffs in the AFC Divisional Round last season. 

All of that is combined with the personal training Mayfield, 26 and still growing in strength, completed for himself over the offseason to position himself for what could be his best season yet in Cleveland.

"I think Point A to Point B is going to happen quicker," Mayfield said. "It's just going through my reads and not forcing anything, much like the mentality I had the second half of last year: Find the open guy and go through my progressions every play."

The Browns would be thrilled if Mayfield can replicate the success he had in the second half of last season: 15 touchdowns and two interceptions in the final 10 games, including two playoff games. By the end of the year, Mayfield passed for 3,563 yards, 26 touchdowns and eight interceptions — a career-low.

He expects those numbers to be even better this season.

He'll have one more receiver capable of helping him get there, too. 

Odell Beckham Jr., back from a season-ending knee injury suffered in Week 7 last season, has impressed those around him with his return to the field. His speed and elite catching abilities were missed in the second half of the year despite the Browns' offensive success, and he's looked healthy, quick and effective in practice as the Browns have gradually worked him back into team drills.

"His catching ability speaks for itself, but people forget how truly fast he is and to be able to take the top off defenses," Mayfield said. "Safeties have to worry about that. Teams will have to defend that and pick their poison because we are a physical and talented run-first team, and that's not going to change no matter who we have out there at receiver. He adds an element to where teams have to decide."

The Chiefs will be their first challenge. For Mayfield and the Browns, the biggest task might be staying ahead of Patrick Mahomes and his array of perennial offensive Pro Bowlers. The group, featuring WR Tyreek Hill and TE Travis Kelce, has held the AFC Championship crown for two seasons and boasts one of the best offenses in recent memory.

The Browns hope to build a similar, long-lasting dynamic with their own offense, but they know they can only focus on one game at a time, and they're confident they'll take another step in that direction in 2021.

Just ask Mayfield.

"The people we've brought in and the pieces, culture-wise, it's been great for the team and franchise," he said. "It needs to continue to head that way, and that's one of my biggest jobs."