NFL teams will never admit to overlooking weaker opponents, but the Chicago Bears, Atlanta Falcons, and Dallas Cowboys all played yesterday as if they thought they could sleepwalk through their games and still win. Instead, all three teams lost big upsets that muddled the NFC playoff picture.

The Bears were the day’s biggest story. After their 7–0 start, they had both scored more points and allowed fewer points than any team in the league, and some commentators suggested they could finish this season a perfect 16–0. Yesterday they were heavy favorites against the Miami Dolphins, who came into the game sporting a 1–6 record. Instead, Miami dominated from the beginning and cruised to a 31–13 win.

Chicago quarterback Rex Grossman practically gave the game away, throwing three interceptions and losing a fumble. Although Grossman has looked at times like he is developing into a top-notch quarterback, he has a hard time adjusting to pressure. Miami sacked him only three times yesterday, but the Dolphins’ relentless pass rush often forced him to throw the ball before he had his feet firmly set, and when he did he was painfully inaccurate. Miami defensive end Jason Taylor was particularly relentless, sacking Grossman once, forcing a fumble, and intercepting a pass that he returned for a touchdown. With Taylor constantly in his face, Grossman finished the day completing just 18 of 42 passes.

Chicago’s defense was its usual aggressive self, but Miami offensive coordinator Mike Mularkey developed a game plan that accounted for Chicago’s frequent blitzing. Miami quarterback Joey Harrington threw mostly short passes after three-step drops, which didn’t give Chicago’s pass rush time to get to him, and the Dolphins called several handoffs to Ronnie Brown that were designed to look like they were going to pass. Chicago’s blitzing linebackers were often in the backfield before they realized that Harrington had already handed off to Brown. Harrington’s numbers (16-of-32 for 137 yards, with three touchdowns and two interceptions) were mediocre, but Chicago never sacked him. Brown’s numbers were superb: His 157 rushing yards made yesterday the best game of his career.

Despite the loss, Chicago remains a virtual lock to win the NFC North after the secondplace Minnesota Vikings themselves suffered a 9–3 upset loss at the hands of the San Francisco 49ers. But the loss does mean that when they take on the Giants on Sunday, the Bears will be playing to preserve their lead in the race for home-field advantage in the NFC.

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Dallas’s Bill Parcells coached against Washington’s Joe Gibbs for the 23rd time yesterday, and the Redskins’ victory on the last play of the game made it the most bizarre ending in the coaches’ rivalry. With the score knotted at 19–19, each team attempted and missed a potentially game-winning field goal in the final 35 seconds, but a Washington block combined with a Dallas penalty allowed the Redskins to try one more kick with no time remaining, and that one gave Washington the 22–19 win.

“I don’t know if I’ve experienced anything like that,” Gibbs said after the game.”I’ve never seen a finish like that.”

Washington receiver Santana Moss missed the game with a hamstring injury, and losing his favorite receiver might actually have helped quarterback Mark Brunell, who showed patience in reading through his progressions. Brunell hit six different receivers in completing 14 of 23 passes for 186 yards, with one touchdown and no interceptions.

The best quarterback on the field, though, was Tony Romo of the Cowboys, who removed any doubt that Parcells did the right thing in benching Drew Bledsoe two weeks ago. Romo completed 24 of 36 passes for 284 yards with two touchdowns and no interceptions. More importantly, Romo showed the mobility Bledsoe lacks, especially on a third-and-12 conversion when he scrambled to avoid the Washington pass rush and then found running back Marion Barber open for a 24-yard gain.

Terrell Owens no doubt prefers Romo to Bledsoe because Owens catches more passes with Romo calling the signals. Owens caught seven passes yesterday after catching nine last week in Romo’s debut as the starter. He never caught more than six in a game from Bledsoe. Owens scored a thirdquarter touchdown but drew Parcells’ ire when he got a 15-yard penalty for his celebration after the score.

The game does more than just add an exciting (and perhaps final) chapter to the Parcells-Gibbs rivalry. It also improves Washington to 3–5 and drops Dallas to 4–4, giving the 6–2 Giants a big lead in the NFC East.

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The Detroit Lions have had a series of high-profile firstround draft busts, but two first-round picks who have delivered, Kevin Jones and Roy Williams, ran wild against Atlanta’s defense yesterday. Jones had 110 rushing yards and two touchdowns, and Williams had 138 receiving yards and one touchdown as the Lions beat the Falcons 30–14.

Lions offensive coordinator Mike Martz helped spring Jones by adding a new wrinkle to the offense, using a formation with six linemen on some running plays. One such play was a 35-yard Jones touchdown that gave Detroit a 10–0 lead. Atlanta responded to the Lions’ emphasis on running by bringing its safeties closer to the line of scrimmage, and that helped Williams get open deep.

Atlanta quarterback Michael Vick threw two interceptions and lost a fumble, and he completed just 17 of 32 passes for 163 yards. Although he ran 10 times for 80 yards, Detroit prevented the left-handed Vick from making his signature play, rolling to the left and passing on the run, by repeatedly keeping a linebacker to Vick’s left to contain him.

At 2–6, the Lions aren’t in the playoff race, but Martz finally has the offense showing signs of life after the team spent tens of millions of dollars on young offensive players who never became stars. Atlanta dropped to 5–3 and a game behind the New Orleans Saints in the NFC South after the Saints beat the Tampa Bay Buccaneers 31–14.

One game doesn’t make the Dolphins, Redskins, or Lions good teams, and one game doesn’t make the Bears, Cowboys, or Falcons bad teams. But one autumn Sunday can show that in the unpredictable NFL, even last-place teams can affect the playoff race. And one autumn Sunday can show that until they could get past the 2006 version of the team, no one should have compared the Bears to the undefeated 1972 Dolphins.

Mr. Smith is a writer for FootballOutsiders.com.