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The Chiefs, winners of their first nine games of 2013 and favorites in all but one of those contests, are underdogs of more than a touchdown on Sunday at Denver at various Nevada sports books, according to “The Linemakers” of Sporting News.

The Chiefs-Broncos line sent us to our leather-bound, rich-mahogany-smelling point spread archives to answer this question: Has a team that has started 9-0 ever been an underdog of more than a TD this late in the season?

The answer is yes. But it’s complicated, as you’ll see.

Using a list of other 9-0 teams from a recent Kansas City Star story as a jumping-off point, and using point spread archive data from handicapping services Jim Feist and Marc Lawrence dating back to 1985, we found the 2013 Chiefs are the fifth team to be an underdog of more than seven points after starting 9-0. In short, we are considering all games after the ninth game of the season, including postseason contests.

So how does this get complicated? Well, in several instances, teams that started 9-0 eventually rested starters late in the regular season before reaching the playoffs.

In this vein, we have the 2005 Colts, the 2009 Colts and the 2009 Saints.

All three clubs were big late late-season underdogs. The 2005 Colts were 9.5-point underdogs at Seattle in Week 16. The 2009 Colts were eight-point underdogs at Buffalo in Week 17, while the 2009 Saints were 10-point underdogs at Carolina in their regular-season finale.

So who’s the fourth past underdog of more than a TD to start 9-0?

A Super Bowl champion, as it turns out.

The Giants were eight-point underdogs at San Francisco in the 1990 NFC title game. The Giants prevailed 15-13, then went on to beat the Bills in Super Bowl XXV as 6.5-point underdogs.

Time will tell how the 2013 Chiefs turn out. But here’s what Sunday’s line tells us: the 9-0 record is nice, but they’ve got some proving to do.