Mayor de Blasio was joined by some talented ballet performers for an unforgettable performance.

Stephen Lovekin Getty Images

After his New York Mets lost the World Series to the Kansas City Royals, New York City Mayor Bill de Blasio knew he had something to do...so he made good on the wager he and Kansas City Mayor Sly James agreed upon before the Fall Classic.

Earlier this week, video surfaced online of de Blasio singing the Leiber and Stoller classic 'Kansas City' while flanked by students from the American Ballet Theatre.

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Witness the performance, which also features de Blasio wearing a Royals jersey, below:

As de Blasio says in the beginning of the clip, 'a bet's a bet'!

(h/t Royals Review)