They rehearse at night and learn choreography with breathtaking speed. They dance for crowds that extend into the thousands.

Sure, New York City is home to lots of dance troupes, but if you’re a dance fan these two groups may not even be on your radar. Don’t be a snob. The Brooklynettes and the Knicks City Dancers perform intricate choreography during the breaks between quarters of pro-basketball games, in arenas with 360-degree views. And they are not messing around.

“I’m like, you just think we appear and it’s perfect?” said Alyssa Quezada, the coach of the Knicks City Dancers, with a laugh. “Do you know how much work goes into it?”

Hours before the players show up, the dancers measure their spacing on the court. (They use cracks and lines on the floor as a map for their spots.) And they must know their steps.