NFL

Giants QB Manning had lifelong quest to be best

INDIANAPOLIS — The original underdogs, they really did face impossible odds. These were actual dogs, taking part in the actual blood sport of bear-baiting, an especially charming event in 16th century England. A bear would be captured, knocked out, tied up, and two dogs would be sent in to finish him off.

The overdog would go for the bear’s jugular vein. He had a higher winning percentage than the IRS. The underdog would go for the bear’s middle section, and that would present a problem if the bear wasn’t yet dead because, well, the bear’s claws would practically pulverize the poor underdog into a pulpy puppy mess.

And you thought the NFL was a vicious league.

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“We like being the underdogs,” Eli Manning said earlier this week, and we can take it on faith that he means the modern interpretation of the word. “We like being the team that has to continually prove itself. We’ve thrived on doing that for a couple of years now.”

And Eli himself has thrived on that for much of the time we’ve known him, going back to his days at Newman High School in New Orleans when he followed big brother Peyton as the Greenies’ quarterback, to his days at Ole Miss when he followed Peyton into the big-boy Southeastern Conference, to his days in the NFL when he has always played a unique game of catch-up with Peyton.

Peyton wins a Super Bowl one year? Eli wins one the next.

Peyton wins a conference championship a couple of years later?

So does Eli.

And it wasn’t only a fraternal thing. By the time Eli arrived in the NFL, Tom Brady already had won two championships and was fixing to win a third. From the moment the Giants traded for him on draft day 2004, there was an established two-man politburo at the top of the league’s list of premiere quarterbacks. You could rank them by titles: Brady and Peyton. You could cite them by MVP trophies and passing records: Peyton and Brady.

Occasionally another name would drift into their realm. Drew Brees poked his head inside. So did Ben Roethlisberger. Aaron Rodgers crashed the party last year, and this year threatened to take the elevator up to a higher floor and a swankier suite.

Eli? Even after winning a Super Bowl — at Brady’s expense — he has remained an underdog in that conversation. Hell, it took Eli himself — whose default position is unassuming, polite and unfailingly modest — to elbow his way into the conversation. And it’s telling that the quarterback who inspired that uncharacteristic burst of self-confidence was the same one he will square off with in two days.

“Tom Brady is a great quarterback, he’s a great player and what you’ve seen with him is he’s gotten better every year,” he said in a radio interview back in August. “I think now he’s grown up and gotten better every year and that’s what I’m trying to do. I kind of hope these next seven years of my quarterback days are my best.”

And yet . . .

The Giants are still listed as three-point underdogs, even as they’ve clearly emerged as the people’s choice among the locals here in Indiana, even as they seem to be the pick of every neutral observer with an opinion, every casual fan with a bookie’s cell number. And Brady is still considered the prime reason why, as if he might not only throw five touchdowns on Sunday but make a few game-saving tackles and kick a 53-yeard field goal, too.

Even as Eli has earned his elite reputation, Brady resides on a higher plane. Eli married the girl next door; Brady married the girl next door if your home happens to be in the Amazon. Eli has carried these Giants, but Brady elevates those Patriots. Or so the theory goes.

Maybe a duplicate of Super Bowl XLII will change that perception once and forever. Maybe a bookend MVP might alter the conversation for good. One thing we know: Manning will make his run at all of that on Sunday, will take his aim at history.

And unlike underdogs of yore, he will go for the jugular.

michael.vaccaro@nypost.com