When The Flash debuted on The CW in 2014, Grant Gustin's Barry Allen was dubbed The Fastest Man on Earth, after receiving metahuman powers following the S.T.A.R. Labs explosion. Of course, there have been a few who can contest this claim, such as the villainous Reverse Flash (Tom Cavanagh) and now the new Season 2 villain Zoom, a.k.a. Jay Garrick (Teddy Sears). But a new contender has entered the mix: Supergirl (Melissa Benoist). Earlier today, the Supergirl Twitter page debuted a new trailer that teases these heroes will actually race one another to determine who the fastest human really is.

This new footage comes just one day after another brief trailer which showed Kara and Barry meeting for the first time. We also recently saw a Supergirl / The Flash crossover poster, which was essentially a parody of the iconic Superman #199 cover from DC Comics. This story centered on Superman and The Flash set to race to see who the fastest man on the planet truly is, and from the looks of this trailer, it seems this race will be held on the small screen, with Supergirl taking the place of her famous cousin. Superman has been referenced several times during the show, and it's possible that the Man of Steel could make an appearance in this episode as well, but we don't know for certain. There has never been any indication that will happen. (Basically, we're just speculating and making that part up!)

The crossover episode, entitled World's Finest, follows Supergirl joining forces with a lightning-fast-and super dreamy-hero, The Flash (Grant Gustin), to take out two villains. Lost and confused after spiraling from his universe and landing in Kara's, The Flash asks for her help in finding his way back home. Excited to finally come face-to-face with one of the good guys, Kara agrees on one condition: The super-runner has to help her take down her ultra-competitive co-worker and screeching malefactor Siobhan, aka Silver Banshee, and Supergirl's old nemesis, Livewire. Packed with action, excitement, and a bit of super-flirting, this is an episode you do not want to miss. Italia Ricci returns as Silver Banshee alongside Brit Morgan as Livewire.

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This episode will also feature recurring Supergirl stars Jenna Dewan-Tatum as Lucy Lane, Chris Vance as Non and Christopher Showerman as Tor. Ever since Supergirl was picked up by CBS, fans had wondered if it was possible for this series to cross over with Greg Berlanti and Andrew Kreisberg's shows Arrow and The Flash on The CW. While they do air on different networks, both CBS and Warner Bros. Entertainment actually own The CW, with the network's name a combination of the first letters of its parent companies.

This Supergirl and The Flash crossover could open the door for other crossover possibilities with The CW's other superhero shows, such as Arrow and the network's latest series, DC's Legends of Tomorrow. Of course, that will likely depend on how many tune in to World's Finest, airing Monday, March 28. It isn't known if this crossover will be teased or referenced in next week's episode of The Flash, Trajectory, airing March 22, the show's first episode after a month-long hiatus, but we'll have to wait and see. Until then, take a look at this trailer teasing the epic race between Supergirl and The Flash. Who do you think will be crowned the fastest human alive?