Whatever the crowds streaming through Wynwood Walls at Saturday’s art walk were expecting — colorful murals, free wine — they didn’t expect this: a phalanx of sultry dancers moving in taut unison to seductive tango music, a sensual dance fantasy emerging suddenly from the mass of shuffling art viewers.

“Wow, they’re good,” asked one woman, eyeing a line of lean men over her cellphone camera. “Who are they?”

They were members of Miami City Ballet, in their first flash mob performance. Their surprise show, an excerpt from Paul Taylor’s Piazzolla Caldera, aimed to promote the ballet’s season-opening program at the Adrienne Arsht Center for the Performing Arts this weekend.

MCB dancers Rebecca King and Callie Manning brought the idea to new artistic director Lourdes Lopez, who enthusiastically signed on last week. The company scrambled to pull together the event, which became part of the John S. and James L. Knight Foundation’s Random Acts of Culture program.

Dressed in denim shorts, T-shirts and tank tops, sneakers and sandals, the dancers seemed to enjoy themselves and the sensation they created. They mingled with the crowd beforehand, and afterward rushed out among the startled onlookers, handing out cards offering half-price discounts to the Arsht Center performances.

They’ll dance Piazzolla Caldera as well as Frederick Ashton’s Les Patineurs and George Balanchine’s Apollo at 8 p.m. Friday and Saturday and 2 p.m. Sunday; miamicityballet.org.