KANSAS CITY, Mo. — The only defence the Kansas City Chiefs played most of this season was, well, in defence of their own defence, which gave up so many yards and points that it became a running joke around the league.

Yes, the Chiefs scored in bushels. They also allowed points in bunches.

The fact that they spent most of the season coughing up 30 points and 400-plus yards per game came despite the fact that they excelled at sacking the quarterback. They finished with 52 of them, tied for the NFL lead, thanks primarily to the trio of Chris Jones, Dee Ford and Justin Houston.

Yet things began to change in Week 17, when the Chiefs shut down the Oakland Raiders in a game they needed to win to secure the No. 1 seed in the AFC. And when critics claimed that the Raiders were playing for nothing, the Chiefs backed it up with a defensive gem in the divisional round against the Colts.

Now, that suddenly stingy defence gets its biggest test Sunday against Tom Brady and the New England Patriots.

At stake: A trip to the Super Bowl, the first for the Chiefs in 49 years.

So what changed? How did a Swiss cheese defence that was torched by the Patriots for 43 points in a Week 6 loss in Foxborough suddenly turn into a steel curtain, and just in the nick of time?

"In the last couple of games, the three things we've done is we've limited the explosive plays, we've done a really solid job of tackling and we've had one defensive penalty in two weeks," Chiefs defensive co-ordinator Bob Sutton said. "Those three things allow you to function and go."

Take each one in order.

In the Chiefs' four losses this season, they allowed four plays of 40-plus yards and 21 plays of at least 20 yards. Seven of those came in a particularly dismal defensive performance against the Rams, who ultimately won a 53-50 shootout at the Coliseum in Los Angeles.

But the Chiefs didn't allow a single play over 15 yards against Oakland, and didn't allow the Colts a play over 30 yards. In fact, Indianapolis didn't score on offence until late in the fourth quarter.

Their success in limiting big plays is, at least in part, a byproduct of improved tackling.

Then there are the penalties. After leading the league in total penalties and defensive penalties this season, their defence has been flagged just once over the past two games.

"Most points that are produced in a drive usually result from an explosive play and-or a penalty in the drive," Sutton explained. "The common thing when you look back and say, 'Hey how'd they get down the field?' It's usually you had a (pass interference) here or you gave up a 20-yard run here or whatever it was. So, if you can manage those and do a relatively good job on those things, you put yourself in a good position to play. I think the guys that have played have done a good job."

Ah, there's the caveat: The guys who have played have done a good job.

The Chiefs have been missing pieces on defence the entire season, and often they have been crucial playmakers. Highly paid linebacker Justin Houston, who had a pair of sacks against the Colts, missed four games with a hamstring injury. Top cornerback Kendall Fuller missed a game with a broken hand. Starting safety Daniel Sorensen missed half the season with a broken leg.

Those injuries alone are enough to derail any defence, but the Chiefs have also played almost the whole season without Eric Berry, their star safety and arguably the team's emotional leader.

He played in just two games because of his heel but is poised to play Sunday against New England.

"That's my guy. Eric Berry has kind of taken me under his wing since I got here," Chiefs cornerback Steven Nelson said. "We call him 'Coach' in our room because he's so knowledgeable. He means a lot to our team and our defence, so whenever we can have him out there, it's a great thing."

The Patriots are under no preconceptions the defence they marched up and down the field against in Week 6 will show up on Sunday. Bill Belichick said this week that there is little to glean from that win, while Brady was quick to heap praise on a defence playing its best all year.

"We've played them quite a bit over the years," the Patriots quarterback said. "They've had some incredible units that we've played against. They've got play-makers at each level. Obviously, a good scheme. They make you work for it. It's a very tough, hard-nosed team. They compete on every snap. They've been in a lot of close games this year. It's a great challenge for us. I don't think you can take anything for granted."

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