Power Rankings: How do you spell unbeaten? D-E-F-E-N-S-E

Updated Sept. 30

Take a look at the top three teams in the CBSSports.com Power Rankings. The New York Giants, Tennessee Titans and Buffalo Bills are all undefeated, the only three teams without a loss.

They also have something else in common, which is why they are where they are -- it's called defense.

As much as I hate to admit it, since I am a connoisseur of offense, defense is ruling the NFL early on.

As we raced to anoint the Dallas Cowboys as the team to beat, we lost vision of their so-so defense. Buried under their high-scoring, fun-to-watch offense is the Cowboys' 20th-ranked scoring defense, which is giving up 22.2 points per game.

The top three teams in the rankings are all in the top 10 in scoring defense. The Titans are tops in the league with an average of 11.3 points allowed, followed by the Giants, who are tied for second with Baltimore at 14.3. The Bills are sixth at 15.8.

Those three are also in the top 10 in sacks, with the Titans tied for second with the Steelers at 15, the Giants have 13 in three games to tie for fourth with the Jets and the Bills have 10 to tie for 10th with three other teams.

Getting after the quarterback is a must in this NFL. The three top teams in our rankings show just how important.

Which unbeaten team has the best defense? Bills 15% Giants 27% Titans 58% Total Votes: 48,576

The Cowboys fell from the top spot to No. 5 by losing to the Washington Redskins. Washington, which has won three consecutive games, is a big mover in these rankings, jumping from 12th to fourth.

They're not like the top three teams. They are 15th in scoring defense and have just six sacks to rank tied for 23rd with three other teams.

The Redskins are making their move behind young quarterback Jason Campbell. He has developed into a capable passing threat that gives them a chance every week.

I love watching the Cowboys' offense, but even I know a 20th-ranked defense isn't good enough. If that defense doesn't improve, their perch in the top five won't last long.

The Power Rankings though Week 4:

RANK	TEAM		MOVE (LW)