Associated Press

We're about a quarter of the way through the NFL seasons. What have we learned? You shouldn't count underdogs (like San Francisco) out. Old powers like Pittsburgh and apparent super-teams like Philadelphia aren't what they seemed. And until someone beats them, the Packers are still the best team in the league. Read on for the rest of our top 10 rankings for Week 5.

10 San Francisco 49ers (3-1)
Associated Press

It's crazy to think about, but the Niners are an overtime loss to the Cowboys away from being 4-0. They showed surprising grit in their comeback win over the Eagles. Upcoming games against Tampa and at Detroit will be telling.

9 Tennessee Titans (3-1)
Associated Press

Matt Hasselbeck has resurrected his career in Tennessee, but a season-ending injury to Kenny Britt and a continued lack of production from Chris Johnson could cause trouble in a hurry.

8 Buffalo Bills (3-1)
Associated Press

The Bills were probably due for a letdown, and they got one in Sunday's loss to the Bengals. We'll see if this young team can bounce back against a reeling Eagles team this week.

7 San Diego Chargers (3-1)
Associated Press

Former Ute Eric Weddle and the Chargers have recovered from an early loss to the Patriots, but they now embark on a three-game road trip before returning home to face the Packers. Tough times ahead.

6 Houston Texans (3-1)
Associated Press

Houston won a surprising defensive struggle over Pittsburgh last week. Now they play host to a tough Raiders team, and they will have to do so without star receiver Andre Johnson.

5 Baltimore Ravens (3-1)
Associated Press

The Ravens' D scored three touchdowns in a win over the suddenly struggling Jets. Now they'll rest on their laurels with a bye this week before a big showdown with the Texans.

4 New England Patriots (3-1)
Associated Press

You can't keep the Pats down for long -- they rebounded from their loss to the Bills with a hard-fought victory over the Raiders. A huge AFC East matchup with the Jets looms this week.

3 New Orleans Saints (3-1)
Associated Press

The Saints marched to an easy win over the Jaguars last week. Now they head to Carolina to face Cam Newton and the Panthers. Expect offensive fireworks.

2 Detroit Lions (4-0)
Associated Press

Yep, they're for real. Detroit came back late to beat the Cowboys in Dallas, and with three straight home games starting this week, the Lions can really plant their flag as NFC title contenders.

1 Green Bay Packers (4-0)
Associated Press

Aaron Rodgers threw for four TDs and ran for two more against the Broncos last week. If he keeps up that form, the Packers are unstoppable. They're a cut above everyone else in the league.