Broncos' D fuels remarkable turnaround

The Denver Broncos have turned things around so quickly under Josh McDaniels and Kyle Orton that Bill Belichick must worry his former pupil could imperil his playoff positioning later in the season. New England (3-1) plays at Denver (4-0) on Sunday in the game of the week.

A win or a loss in the showdown won't define McDaniels' start in Denver. The Patriots' former offensive coordinator has exceeded expectations by winning his first four games. His defense, in particular, has exceeded expectations.

McDaniels' hiring of Mike Nolan as defensive coordinator has proved to be brilliant. Nolan has turned a bunch of castoffs into a respectable 3-4 defense. The Broncos have no-names on the defensive line and older, big-name players in the secondary but have allowed only 26 points this season. Denver gave up 28 points a game in 2008.

McDaniels, of course, got in hot water with Denver fans by flirting with trading for Matt Cassel and later dealing Jay Cutler to Chicago. McDaniels' offseason conversation with Belichick about Cassel resulted in moves that changed the face of the NFL.

The Bears are thrilled with Cutler. But the Broncos' addition of Orton has worked well too. The former Bear has a 97.7 quarterback rating, 906 yards passing and five touchdown passes.

Now on to the rest of this week's First and 10 …

1. Cincinnati Bengals at Baltimore Ravens: During the summer, the Bengals were the stars of HBO's "Hard Knocks." On Sunday, they play in Baltimore to see if they can play a game of hard knocks. The Bengals must be at their physical best to match the hits of the Ravens, who have a physical defense and a big, strong offensive line.

This season has been a roller-coaster ride for the Bengals. They lost on a last-second fluke play to the Broncos to open the season. Cincinnati went to overtime last week after having an extra point blocked that would have given them a one-point lead late in regulation. In overtime, Bengals coach Marvin Lewis had to be talked out of punting on fourth-and-11 from the Browns' 41. Carson Palmer then broke a fourth-down scramble that set up the winning field goal. Yes, the Bengals are improved.

The Ravens probably threw too much last week in a loss to the Patriots, but Joe Flacco almost brought them from behind. With both teams at 3-1, it's a battle for the lead in the AFC North.

2. Atlanta Falcons at San Francisco 49ers: The Falcons used the bye last week to reflect on their defensive problems. Head coach Mike Smith has holes in the secondary and on run defense. He hopes to scheme out some of the problems starting with Sunday's game in San Francisco. The Falcons get a break because halfback Frank Gore won't play. He is out two games with an ankle injury and will be replaced by Glen Coffee, a rookie who's not the threat Gore is.

Mike Singletary will be challenged to stop the Falcons' Matt Ryan, one of the best young quarterbacks in the game. Like the Broncos, the 49ers are trying to prove their good start is for real and that they indeed are playoff contenders.

3. Tennessee Titans at Indianapolis Colts: It's desperation time for the Titans. If they lose Sunday night's game, they will be 0-5 and probably a couple of weeks away from turning the offense over to Vince Young. Next week, the Titans play the Patriots. Tennessee's 0-4 start is one of the bigger surprises this season. Except for the loss of defensive tackle Albert Haynesworth, it's pretty much the same team that won 13 games last year. Mistakes on special teams have hurt, Kerry Collins hasn't been as sharp as last year and the secondary is coming off a terrible month.

The Colts won't be overconfident. Peyton Manning's offense is No. 1 in the league, but Manning knows his numbers usually come down in divisional games because teams in the AFC South aren't surprised by the Colts' passing offense. Expect a close, hard-fought game.

4. Houston Texans at Arizona Cardinals: The Larry Fitzgerald-Andre Johnson showdown should be one of the highlights of the season. Fitzgerald is the game's best receiver. Johnson has averaged 6.62 catches a game since Gary Kubiak took over as Texans coach in 2006. Each receiver will be trying to top the other.

Stopping Fitzgerald and Anquan Boldin will be an interesting challenge for Kubiak. He has changed starters in the secondary every week trying to find the right coverage combinations. He's also demanding more help from a pass rush that has been spotty all season.

Arizona QB Kurt Warner was banged up the first three games, so the bye week gave him a chance to heal. The Cardinals must re-establish some sense of home-field advantage this season. They have lost their first two home games and don't want to fall too far behind in the NFC West race.

5. Washington Redskins at Carolina Panthers: Sherman Lewis was brought in as a new set of eyes for Jim Zorn and the Redskins' offense. It will be interesting to see if his vision can start to get more points out of this offense. The Redskins are averaging only 14.5 points, which is 2.1 less than last season. Frustration is building. The Redskins averaged only 13 points a game against St. Louis, Detroit and Tampa Bay, three of the worst teams in the league.

Carolina enters at 0-3, but on paper the Panthers aren't as weak as the past three opponents that bottled up the Redskins' offense. Carolina coach John Fox needs QB Jake Delhomme to play with confidence and massive DT Hollis Thomas to help contain Redskins running back Clinton Portis. Fox has to win to keep the fan support behind the team.

6. New York Jets at Miami Dolphins: With the addition of WR Braylon Edwards, the Jets, who look great on defense, now have the makings of a decent offense. The Monday night game against the Dolphins will be a good test. Rookie quarterback Mark Sanchez needed a big target to help him when he's blitzed. Edwards could be to Sanchez what Plaxico Burress was to Ben Roethlisberger and Eli Manning. Young quarterbacks need tall, go-to receivers to combat the blitz.

Seeing the success the Saints had blitzing Sanchez in Week 4, the Dolphins will likely bring the heat. This game is crucial for the Dolphins. A loss would drop them to 1-4, and teams aspiring to be in the playoffs can't lose divisional home games. This game also has a revenge factor. Miami, with former Jets quarterback Chad Pennington, beat the Jets in Week 17 of last season to claim the AFC East title and keep New York out of the playoffs.

7. Dallas Cowboys at Kansas City Chiefs: Is Tony Romo regressing as a starting quarterback? It appears so. Despite his strong arm and aggressive style, Romo is making too many mistakes in critical parts of games. Against the Broncos in Week 4, Romo didn't seem to be consistently on the same page as his receivers. Romo is under pressure to start turning his season around.

The Chiefs could be dangerous. Even though they are 0-4, they have great fans and their 3-4 defense could gain confidence if Romo doesn't get off to a good start.

8. Oakland Raiders at New York Giants: The Giants could probably win this game without Eli Manning, but you figure Manning will do his best to play despite his bout with plantar fasciitis. He has played in 82 straight NFL games. This foot problem will nag him for a good portion of the season, so Manning must simply adjust to the pain. The Giants have adjusted to pain all season. They've survived a long injury list that has kept several starters on the sideline.

The Raiders continue to stick with a struggling JaMarcus Russell, and the plan won't change this week. Al Davis believes Russell will grow out of the 40 percent accuracy funk he's been mired in all season.

9. Cleveland Browns at Buffalo Bills: Dick Jauron's job could be on the line Sunday. A loss to the Browns could anger owner Ralph Wilson so much he might want to make a change. Remember, this is the team that fired its offensive coordinator before the start of the season.

The Browns are 0-4, but Cleveland's proximity to Buffalo makes this almost a rivalry game. The Bills have a talent advantage. They also would love to break a 10-game losing streak against 3-4 defenses.

10. Tampa Bay Buccaneers at Philadelphia Eagles: Donovan McNabb is back from his cracked rib. Brian Westbrook is back from his ankle injury. The defense is 100 percent healthy coming off a bye. The 0-4 Bucs are the perfect opponent for a Philadelphia team looking to generate momentum.

John Clayton, a recipient of the Pro Football Hall of Fame's McCann Award for distinguished reporting, is a senior writer for ESPN.com.