Count Mayor Rahm Emanuel as one of the proud Northwestern University alums delighting in the team’s historic Cinderella dance into the second round of their first-ever NCAA tournament.

But the mayor who has a reputation for being ruthless in politics is showing no mercy for the Vanderbilt star whose mistake made it possible: sharpshooter Matthew Fisher-Davis.

“The guy on Vanderbilt needs a witness-protection program,” Emanuel said during a post-game taping for the WLS-AM radio program “Connected to Chicago,” to be broadcast at 7 p.m. Sunday. “How do you foul a guy when you’re up? I don’t get it. He must have had a brain freeze.”

After almost singlehandedly shooting his team back into the game, Fisher-Davis committed an intentional foul against Northwestern’s Bryant McIntosh in the mistaken belief that Vandy was down by one point, rather than up.

When McIntosh proceeded to nail his free-throws, the Wildcats’ improbable victory was sealed.

Afterward, Northwestern head coach Chris Collins took the high road, saying he genuinely felt badly for Fisher-Davis.

After graduating from Sarah Lawrence College in Bronxville, N.Y., Emanuel got his master’s degree in communications from Northwestern.

Now, he’s like so many other proud NU grads, delighting in the team’s success after betting in his own NCAA bracket that the Cats would “make it past this [first] round.”

“Coach Collins and the team — I give ’em a lot of credit,” the mayor said. “When he was recruiting the kids, he said, ‘I’ve got nothing to offer you but a dream and a hope.’ And they signed up for it.’ And that ticket came home.

“I give ’em a lot of credit, and I give the kids a lot for the heart they showed all season — not just now.”

Emanuel said the role Northwestern is playing as the darling of this year’s NCAA tournament has rekindled a sports fire in Chicago previously ignited by the Cubs and Blackhawks.

“There’s a sense of spirit from something like this that has not happened for the Northwestern Wildcats for a long time,” he said. “We’re a great sports town. Between baseball and the Blackhawks and the Stanley Cup playoffs, it is a great sporting event. And there’s nothing like March Madness.”