Every year it is written and every year it is true that the key to every toll gate throughout the National Football League playoffs is a tough defense. Contain the opposition when it counts most and you don't necessarily have to score a lot of points yourself to win. Using that philosophy as a base, here is what probably lies ahead for the eight teams that still have dates this weekend (remembering that weather could well be a factor on Saturday in Chicago and Cincinnati, and on Sunday in Buffalo, but is unlikely to play a major role in Sunday's other game in San Francisco). Philadelphia at Chicago
Most of the pre-game stories make it sound as though coaches Buddy Ryan of the Eagles and Mike Ditka of the Bears are playing each other.
This stems from the fact that Ryan never felt he got proper credit for many of the innovative things Chicago did while he was working under Ditka as the Bears' defensive coordinator. And not all of their arguments on this subject were confined to the privacy of the clubhouse.
So when Philadelphia offered Ryan a six-figure contract three years ago to rebuild the heavier-than-air Eagles, Buddy couldn't wait to accept the challenge. In what has to be considered a major achievement in such a short time, Ryan brought the Eagles home first this year in the NFC East with a 10-6 record.
The key man for the Eagles on the field is quarterback Randall Cunningham, who some people think should be named the league's most valuable player.
Cunningham's ability to run (he was the team's leading rusher this season) combined with a strong and accurate arm make him very difficult to contain throughout an entire game. On Saturday, however, he'll be operating against a defense led by all-pro middle linebacker Mike Singletary that gave up the fewest points (215) this year of all 28 NFL teams.
Furthermore, going into Soldier Field to play Chicago in anything as important as a playoff game is like going into the woods with a bear that hasn't eaten in a couple of days.
Chances are Cunningham & Co. will cause some damage, but not enough to keep the Bears from moving closer to the Super Bowl. Seattle at Cincinnati
While Cincinnati has been only a .500 team on the road, the Bengals are a perfect 8-0 at home. They also have one of the best offensive lines in the league and a quarterback in Boomer Esiason, who takes full advantage of the extra time he gets to throw.
The Seattle Seahawks, if you will pardon the comparison with baseball, are the Los Angeles Dodgers of the NFL playoffs.
On paper it doesn't look as though the Seahawks can win. They have a porous defense, which in five losses this season gave up 24 points or more. But if quarterback Dave Krieg, a 62 percent passer in his last six games, should continue at that pace, things would not be that easy for the Bengals. Minnesota at San Francisco
The Minnesota Vikings, tired of being the Harold Stassens of professional football, appear to have peaked at just the right time.
While the Vikings' offense (particularly the running game) has sometimes been known to disappear for hours at a time, they do have an exceptional defense when it comes to putting extreme pressure on opposing quarterbacks.
In beating Los Angeles, 28-17, in Monday's wild-card game, Minnesota never let Ram quarterback Jim Everett establish anything in the way of rhythm. The Vikings also got two interceptions from strong safety Joey Browner and terrific single coverage from cornerback Carl Lee, who stuffed the Rams' wide receivers the way you would a turkey.
However, stopping the potent San Francisco attack led by quarterback Joe Montana will probably be a tougher assignment. Montana, a 10-year veteran from Notre Dame, knows his way around in big games, as evidenced by the fact that he has already led the 49ers to two Super Bowl triumphs. Making things even tougher for opposing defenses is the fact that running back Roger Craig is having his biggest year. Meanwhile, coach Bill Walsh is a master at mixing up his defenses, and the special teams also generally play well.
Finally, the 49ers have the incentive supplied by what happened in a similar situation a year ago when they posted a 13-2 regular-season record only to be stunned by these same Vikings in their playoff opener. Houston at Buffalo
The Buffalo Bills, with only one victory in their last four regular-season games, have been struggling lately to regain the consistency that made them so formidable earlier in the season.
If this game were being played in Houston, Buffalo would have probable cause to worry. But with the home-field advantage, plus the fact that quarterback Jim Kelly sometimes has spectacular games, the Bills should prevail.
The Oilers will be fired up, though, after going into Cleveland last Saturday (where they had lost the previous Sunday) and playing well enough to beat the Browns in that day's wild-card game, 24-23.
Basically Houston will rely on quarterback Warren Moon and a covey of fine backs to try to upset the Bills.