WATCH: First "Supergirl"/"Flash" Crossover Teaser for "World's Finest"

With the anticipated DC Comics television crossover mere weeks away, CBS has debuted the first glimpse of "World's Finest," the upcoming "Supergirl"/"Flash" crossover episode, starring Melissa Benoist and Grant Gustin.

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Though the two heroes don't quite come face-to-face in the short teaser, Supergirl's "S"-shield does get the Flash's signature lightning treatment.

The Flash's guest appearance is the culmination of nearly a year of fan speculation, starting with a Variety cover from last May where Gustin and Benoist both appeared in costume, months before the "Supergirl" series premiere. Beyond both shows being based on famous DC superheroes, they share two executive producers in common, Greg Berlanti and Andrew Kreisberg.

"Worlds Finest" - Kara gains a new ally when the lightning-fast superhero The Flash (Grant Gustin) suddenly appears from an alternate universe and helps Kara battle Siobhan, aka Silver Banshee, and Livewire in exchange for her help in finding a way to return him home, on SUPERGIRL, Monday, March 28 (8:00-9:00 PM) on the CBS Television Network. Grant Gustin crosses over as The Flash.

The Flash speeds into National City on the March 28 episode of "Supergirl."

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