Arguably, Eli Manning’s performance against the San Francisco 49ers in the 2011 NFC Championship Game was his greatest as a professional and one that will live in New York Giants infamy.

It also almost never happened.

David Carr, the former first-round draft pick who served as Manning’s backup that year, revealed on Sunday that he very nearly started against the 49ers in that game after Manning had come down with the flu earlier in the week.

“We roll into Friday, he’s still sick — can’t practice. He’s literally in the training room getting IVs all day,” Carr said on NFL Total Access. “Has the flu for like four straight days. So I practice on Friday with the team. So now Eli hasn’t had any practice time, I’ve taken all the reps for the NFC Championship Game.

“He shows up on Saturday, looks fine, he goes through the walk-through, goes to the game. Everything is normal. No one knew. He didn’t practice all week.”

Not only did no one know about that at the time, it had remained a complete secret — or at least a relative unknown — until Carr let the car out of the bag this past week.

Manning, of course, went on to throw for 316 yards and two touchdowns in the overtime win, and managed to remain on the field despite being beaten into the ground on nearly every single snap. In fact, at one point, Carr reveals, defensive end Justin Tuck came to him and told him to get ready to enter the game, fearing that Manning would be injured.

Ultimately, Lawrence Tynes kicked the game-winning field goal to send the Giants to Super Bowl XLVI, where they would defeat the New England Patriots for their second Lombardi Trophy in four years.