Kansas City, Mo ? This is what gamblers call a “trap game,” a mismatch so hopelessly one-sided there seems no way for the underdog to even stay close.

Only sometimes they do. Sometimes they even win.

While preparing for today’s game at the winless and seemingly hapless Kansas City Chiefs, one trap game in particular was on the minds of the unbeaten and seemingly invincible New York Giants.

Vivid in their memory is last Oct. 13, when they came breezing into Cleveland with a jaunty 4-0 record and got ambushed, 35-14, by an underdog Browns team that had lost three in a row.

It was a valuable lesson in the perils of overconfidence that could serve them well this afternoon in Arrowhead Stadium.

“We know very well how that felt, going into that stadium undefeated, and maybe we started to feel good about ourselves a little bit more than was warranted,” said defensive end Justin Tuck. “And we went in there and got our butt whupped.”

If anyone on his team has forgotten the lessons of last Oct. 13, Giants coach Tom Coughlin has been careful to remind them.

“The bottom line is don’t get trapped,” said defensive end Mathias Kiwanuka. “The bottom line is no matter how good you think you are, you have to go out there and perform on Sunday.”

That’s true, of course. But the Chiefs are locked in a third straight year of sub-mediocrity, losers of 26 of their last 28, and 81/2-point home underdogs for a reason.

They’ve had trouble doing almost everything. Their offensive line, particularly the right side, has been a shambles.

The Giants, playing their third straight road game, are coming off a 24-0 shutout at Tampa Bay. They haven’t had a turnover or allowed a sack in two weeks.

But the Chiefs were so overmatched during a 34-14 loss last week at Philadelphia, first-year coach Todd Haley was accused of waving the white flag because he more or less abandoned the passing game in the second half to keep quarterback Matt Cassel from getting hurt.

A few months from now, everyone might look back at this one as the day the best team in the NFL played the worst.

“I am not falling into any of that nonsense,” said Giants guard Chris Snee. “I look at that defense and see four first-round picks, a second-round pick and guys up front that I have to deal with. I am not getting caught up in any of that.”