Five teams entered, one team left.

Though the stakes weren’t quite as dire as Thunderdome, five teams began Week 4 without a loss and only one escaped unscathed – the Arizona Cardinals.

While one team was ensured of picking up its first loss – with the Cardinals visiting the then-3-0 Los Angeles Rams – the other three previous unbeatens – the Carolina Panthers, Denver Broncos and Las Vegas Raiders – all stumbled in their quest to keep their perfect records intact. And none of the outcomes were particularly close with the Rams, Panthers, Broncos and Raiders losing by an average of 13.75 points.

The Cardinals, obviously, had something to do with that lopsided scoring margin, piling up 465 yards in cruising to a 37-20 victory at SoFi Stadium to keep their record unblemished. And as the league’s last standing unbeaten, this is the first time since 2017 that there’s only one undefeated team after four weeks.

Number of Undefeated Teams by Year after Week 4 – Since 2015

Season# of UnbeatensUnbeaten Teams
2021 1Cardinals
20206Bills, Packers, Chiefs, Steelers, Seahawks, Titans
20193Chiefs, Patriots, 49ers
20182Chiefs, Rams
20162Broncos, Vikings
20156Falcons, Panthers, Bengals, Broncos, Packers, Patriots

Arizona is four games into a 17-game season with a winning percentage of 1.000, behind an offense that leads the NFL in scoring and total yards, making it the first team since the 1953 Cleveland Browns to be the league’s sole leader in scoring offense, total offense and winning percentage after four games.

Eyeing its first 5-0 start since reeling off seven consecutive victories to start the 1974 season, Arizona is heavily favored in its matchup with the visiting San Francisco 49ers, who will likely be turning to Trey Lance for his first start with Jimmy Garoppolo nursing an injured calf. It will be fun to tune in to the game for a bit to see what the third pick of this past April’s draft is capable of, but overall, we don’t have it projected too high on our watchability index.

Well, what pray tell do you suggest I watch then? We’re glad you asked.

Green Bay Packers vs. Cincinnati Bengals (Sunday, 1:00 ET, FOX)

Reasons to watch: For starters, it’s the only game from Sunday’s early slate to feature both teams sporting 3-1 records, but on top of that, it’s an intriguing matchup. While the Packers have been rolling along since their Week 1 debacle, the Bengals are seeking a signature win having played the easiest schedule of any team thus far with a .250 opponents’ winning percentage. Cincinnati will also have some extra time to prepare for this game having been off since last Thursday’s win over the Jacksonville Jaguars.

Green Bay’s recent success as had a lot to do with the play of none other than Aaron Rodgers. Big surprise. The reigning league MVP threw a pair of touchdown passes to Randall Cobb in last week’s 27-17 win over the Pittsburgh Steelers to give him eight TDs to zero interceptions during Green Bay’s three-game winning streak. Since that ugly 36.8 QB rating he registered in the season opener, Rodgers’ 119.4 QB rating trails only Dak Prescott’s 128.9 for the best in the NFL since Week 2.

His counterpart, Joe Burrow, had a dud performance of his own – a three-interception game in a Week 2 loss to the Chicago Bears – but has a 133.1 QB rating in Cincinnati’s three wins. He threw for a season-best 348 yards against the Jaguars, and since that setback at Soldier Field, Burrow ranks second in well-thrown percentage (88.0) and second in catchability percentage (86.0) among all QBs with at least 40 attempts. Well-thrown percentage measures how often a quarterback makes an accurate, on-target throw, while catchability percentage measures how frequent a pass is catchable.

Key matchup: The wide receivers vs. the defensive backs

The big question for the Bengals is who will guard Davante Adams. Since Week 2, Adams leads the NFL with 26 receptions and his burn percentage of 73.7 ranks sixth among all receivers that have been targeted at least 20 times, while his 413 burn yards are fourth most. Burn yards calculate when the targeted receiver does his part to achieve a successful play regardless of the quality of throw by the quarterback. Keeping Adams in check is no easy task, and the Bengals will likely be counting on Chidoe Awuzie to cover the four-time Pro Bowler. Awuzie, who is slated to return after missing the Jacksonville game with a groin injury, is off to a solid start to the season, compiling a burn-allowed percentage of 41.2 while the league average sits at 53.4. Burn-allowed percentage measures the rate at which a defender allows the targeted receiver to achieve a successful play, regardless of the quality of the throw by the quarterback. However, he hasn’t faced anyone as dangerous as the combination of Rodgers and Adams. The Bengals have gone up against the inexperienced Trevor Lawrence, the aging Ben Roethlisberger, the dysfunctional Andy Dalton-Justin Fields tandem (though the Bears have finally chosen to go with Fields) and the serviceable Kirk Cousins, who they allowed to carve them up for 351 yards. All-in-all, those QBs don’t exactly strike fear into the hearts of opposing defenses.

While the Bengals aren’t really sure what they have in their secondary, the Packers know what they have in cornerback Jaire Alexander, and they shudder to think what life will be like without the 2020 Pro Bowler. Unfortunately for the Packers, Alexander is dealing with a shoulder injury and is expected to miss this game and could possibly undergo season-ending surgery. Since his 2018 rookie season, Alexander’s 44 passes defensed rank fourth in the NFL. This year, when in man coverage on a receiver, Alexander has prevented his man from being open 25 of 28 times, and when he’s in the lineup, the Packers pass defense projects to successfully cover receivers at the seventh-best rate in the NFL. When he’s removed from the lineup and replaced with a backup, the Packers coverage drops to 29th. An Alexander-less secondary certainly bodes well for the Bengals with Tee Higgins looking like he’ll return from a shoulder injury, coupled with Ja’Marr Chase’s big-play ability. Chase already has one reception of 25 or more yards in each of Cincinnati’s first four games and has a burn yards to target average of 14.08 – fourth highest in the NFL among receivers that have been targeted a minimum of 25 times.

Highest burn yards per target

Cleveland Browns vs. Los Angeles Chargers (Sunday, 4:05 ET, CBS)

Reasons to watch: It’s another matchup between 3-1 teams, and these two are legitimate contenders to dethrone the Kansas City Chiefs in the AFC. While the Browns followed up their loss to the Chiefs in a divisional-round game last season with a discouraging defeat at Kansas City in Week 1, they’ve been perfect since. The only problem is those wins haven’t come over the stiffest competition, with victories over the Houston Texans, Bears and Minnesota Vikings. Baker Mayfield has looked rather ordinary and apparently with good reason, as it was revealed Thursday that he’s been playing with a torn labrum in his non-throwing shoulder. The plan is he’ll continue to play with it along as it doesn’t get any worse, though, it’s hard to imagine it not being a target of Joey Bosa and company given the way he treated Las Vegas Raiders quarterback Derek Carr this past week.

Unlike the Browns, the Chargers went into Arrowhead Stadium this season and came away with a win, and then knocked off the previously unbeaten Raiders on Monday to open 3-1 for the first time since starting 5-1 in 2014. Justin Herbert will be making his 20th career start in this one and is showing the poise of a veteran, throwing seven touchdowns without an interception in the last two games. The Los Angeles defense recorded five takeaways against Kansas City and Las Vegas and smothered Carr, limiting him to 196 passing yards while sacking him four times, after he came in averaging a league-best 401.0 passing yards per game. Monday marked the eighth straight game the Chargers forced at least one turnover – the third-longest active streak in the NFL – and they are 7-1 in that span.

Key matchup: The lines

Even if Mayfield’s left shoulder wasn’t hurting, Cleveland’s formula for success is its run game. With 52.8% of their plays being rushes, the Browns are one of two teams to run the ball more than they throw it (the New Orleans Saints being the other at 57.8%). The reason the Browns keep the ball on the ground is fairly obvious, because it works. Cleveland has the NFL’s fourth-best run-blocking unit, and a pair of bruising backs in Kareem Hunt, who leads the league with an average of 3.20 yards after contact, and Nick Chubb, who ranks eighth at 2.27 (min. 30 carries). Chubb has racked up 388 scrimmage yards and Hunt has 355, giving the Browns just the second running back duo in the last 30 years to have at least 350 scrimmage yards apiece over their team’s first four games. All of this spells trouble for a Los Angeles team that is vulnerable stopping the run, ranking 27th in run defense personnel in terms of winning one-on-one blocks and beating double teams.

When the Chargers have the ball, the matchup to watch is Browns edge rusher Myles Garrett going up against rookie left tackle Rashawn Slater. Garrett’s exploits are well documented, as he ranks first in the NFL in sacks (6.0), is tied with the Raiders’ Maxx Crosby for second in QB hits (13) and is third in QB knockdowns (12.0). The Chargers have done a good job of keeping Herbert upright this season after he was sacked 32 times as a rookie in 2020 – tied with Burrow for the ninth most. This season, Herbert is sacked on 4.1% of his dropbacks – the seventh-lowest rate in the league among those with at least 80 attempts.

Buffalo Bills vs. Kansas City Chiefs (Sunday, 8:20 ET, NBC)

Reasons to watch: A rematch of last season’s AFC championship game would be a good place to start. Josh Allen and the Bills arrive at Arrowhead flying high after routing the hapless Houston Texans 40-0 for their second straight 40-point performance and third win in a row. Despite losing to the Pittsburgh Steelers by a touchdown in its season opener, Buffalo still has a plus-90 scoring margin on the season – the third largest through four games since the turn of the century.

Highest Point Differential in First Four Games of a Season – Since 2000

Year/TeamPoint DiffHow Season Ended
2007 New England Patriots+100 (148-48)Lost in Super Bowl
2019 New England Patriots+95 (122-27)Lost in Wild Card
2021 Buffalo Bills+90 (134-44)TBD
2013 Denver Broncos+88 (179-91)Lost in Super Bowl
2006 Chicago Bears+87 (116-29)Lost in Super Bowl

That’s all well and good but it’s no secret the Bills have been steamrolling overmatched opponents with each of the last three using a backup quarterback. That ends with Patrick Mahomes and the Chiefs, who are coming off a 42-30 road win over the Philadelphia Eagles. With five TD passes last week, Mahomes has accounted for 15 of Kansas City’s 18 touchdowns, which are the most by any team this season. The Chiefs would probably say they should have more if not for the turnovers, which has been the team’s biggest detriment. They have six giveaways in their two defeats and just one in their two victories.

Key matchup: Passing Offenses vs. Passing Defenses

Although Mahomes already has four interceptions – two fewer than he had all last season – the 2018 NFL MVP has, for the most part, still been his same impressive self. Among QBs with at least 60 attempts, his QB rating of 119.6 ranks second in the NFL, along with his well-thrown percentage of 84.8, while his open-target percentage of 83.3 ranks fourth. Open target percentage measures how often the targeted receiver is open. He’s playing behind an offensive line that boasts the 11th-best pass protection unit while the Bills lay claim to the league’s sixth-best pass rushing unit with 55 QB hurries. Overall, it will be strength vs. strength when the Chiefs have the ball.

Allen has shrugged off his slow start and is now picking apart opposing defenses. After averaging 224.5 passing yards with three touchdowns and a 77.9 rating in Buffalo’s first two games, he’s averaging 303.0 throwing yards with six TDs and a 117.7 rating in the last two.

Stefon Diggs is Allen’s top target (tied with the Atlanta Falcons’ Calvin Ridley for sixth in the league with 42), but he’s just one of many weapons. Among wide receivers with a minimum of 25 targets, Emmanuel Sanders’ burn percentage of 73.1 ranks fifth in the league, while Cole Beasley’s open percentage of 87.5 ranks third. Open percentage measures how often a receiver is open on throws in which he’s targeted. As scary good as the Chiefs have been offensively, their defense has been just ghastly. Kansas City is permitting an NFL-worst average of 6.87 yards per play and has surrendered a league-high 39 plays of 15 or more yards. The Chiefs expect to get cornerback Charvarius Ward back after he missed the last two games with a quad injury and that would be a godsend for their much-maligned defense. With Ward on the field, Kansas City’s defense ranks eighth in pass coverage, but without him, it tumbles down to 25th in the league.

Kyle Cunningham-Rhoads and Greg Gifford contributed. Design by Matt Sisneros.