There was a point through the first two months of the season when most NFL experts seemed convinced the playoff scenarios were a foregone conclusion.
The Steelers and Patriots were running away in the AFC. The Eagles and Falcons were doing the same in the NFC.
This was going to be easy, right?
Well, after 17 weeks of winning and losing streaks, record performances, perplexing losses and critical injuries, the NFL enters its postseason with a little less certainty.
The four No. 1 seeds are still formidable, but they are mortal.
The Steelers, the cream of the crop at 15-1, will hang some of their hopes on a slightly banged-up rookie quarterback named Ben Roethlisberger.
A strong defense, prolific running game and home-field advantage will have to help.
"Playing at home is the biggest thing," coach Bill Cowher said. "We are very comfortable playing at home in front of our fans. There is a lot to be said for that. It's an advantage for your defense because of the noise factor and how loud it can be."
The Patriots, who made winning streaks look like the norm, lost to the Dolphins 29-28 Dec. 20 when quarterback Tom Brady threw four interceptions.
They also enter the playoffs with the added distraction that offensive coordinator Charlie Weis is headed to Notre Dame when the season is over.
"It's very different than the regular season. That's what I've learned in the last four or five years," Brady said in Foxboro. "You work so hard to get this opportunity, and now it's here. Regardless of what's going on in your life, this takes total control of it. And it's fun, because you realize you can't afford to make any mistakes."
The Falcons' success or failure depends on the feet of quarterback Michael Vick, who took a hammering in the last two games he played. And the Eagles, expected to finally make it to the Super Bowl after dropping three straight NFC Championship Games, will have to do it without injured receiver Terrell Owens.
"I feel very confident about the group," Eagles coach Andy Reid said. "That is hard because I felt very confident in the other groups, too, going in. I have a lot of trust in them and I know they are going to work hard and come out and play hard. ... I've got some tremendous leaders in that locker room, and guys will be very focused in on what is at hand."
All four games over wild-card weekend feature teams that have played each other at least once during the regular season.
After turning around a 4-12 season to an AFC West crown, the Chargers (12-4) host the Jets (10-6) at 8 tonight.
San Diego has earned the right to host an opening-round game by putting up impressive offensive numbers and playing opportunistic defense.
But Pro Bowl quarterback Drew Brees, who passed for 3,159 yards and 27 touchdowns, is about to play his first career playoff game.
"I think that the challenge is just in your mind," Brees said. "It's being calm and cool and saying, "Hey, it's just another game.' What you try to do throughout the season is prepare for every game like it's the Super Bowl, so that when you do encounter (playoff) games ... it's just like any other game. That way, you keep from putting extra stress or extra pressure on yourself."
Though favored, the Chargers enter the playoffs under another cloud: the 5-11 playoff record of coach Marty Schottenheimer.
"People are always going to come up with reasons to criticize," Brees said. "You look at how successful Peyton (Manning) has been as a quarterback and how successful Marty has been as a coach. There's no doubt that Marty and all of us have the ability to go out and win a championship."
Behind Manning, the Colts (12-4) are the league's top-scoring team and are expected to present all kinds of matchup problems for the Broncos (10-6), whom they host at 1 p.m. Sunday.
On the other hand, Denver did bolster its defense with the offseason acquisitions of defensive backs Champ Bailey, via trade, and John Lynch, via free agency.
Lynch was fined $75,000 for a hit on tight end Dallas Clark last week, a clear indication of one strategy for dealing with the Colts receivers.
"They don't like to be hit," strong safety Kenoy Kennedy said. "They're small guys. Any time they can, they jump on the ground. You've got to be physical with them. They don't like it."
Then there's the NFC and this weekend's rematches of division games .
Today at 4:30 p.m., the Rams (8-8) play the Seahawks (9-7) for the third time this season. The Rams swept the season series.
"I think our record doesn't matter at this point," Rams coach Mike Martz said. "That's what we've been telling our players all year long. It's just who's playing well now, not how you're playing in September or November, or whether you're 15-1."
Picking the winner between NFC North rivals Green Bay (10-6) and Minnesota (8-8), who play at 4:30 p.m. Sunday, isn't any easier. The Packers swept the Vikings this season, but both games came down to Green Bay field goals in the final seconds.
Minnesota is in the midst of another late-season swoon, and the Packers know the Vikings have nothing to lose.
"We're going to go out there and just try to execute the game plan and do everything possible to beat the Vikings," quarterback Brett Favre said. "They're going to throw some new things at us that we haven't seen yet. But all we can do is prepare like we did last game, and hopefully the results are the same."
Information from other news organizations was used in this report.