Robbie Amell's Instagram post - the latest one - has revealed that his cousin Stephen Amell was actually the first to know about his casting as Firestorm in CW's upcoming series "The Flash."

It seems that "Arrow" lead actor Stephen Amell and his "The Tomorrow People" star cousin Robbie are pretty close, such that the first person to find out about their new projects is one or the other.

In Robbie Amell's Instagram post, which he posted today, the 26-year-old hunky actor shared to his fans and followers that his cousin Stephen was the first to know about his confirmed casting for "The Flash."

"As usual @amelladventures was the first to know. Best text ever. #TheFlash #Arrow #Firestorm," RObbie Amell's Instagram post read.

He also shared a screen grab of Stephen's text message to him, which says, "Welcome to the Justice League of America."

After Robbie Amell's Instagram post was uploaded, his fans were quick to respond congratulatory messages to his great news.

"Good luck on ur role #Firestorm," a brittanyhope007 wrote.

"That's awesome dude can't wait to see you on The Flash @robbieamell!!" Instagram user dogdude12 commented.

"Aaaaaaaaahhhhh!!! Best news! hdjwnskdbsb," _lilgee14 exclaimed.

Robbie Amell made headlines early today when it was revealed that he got cast as Firestorm on the upcoming "The Flash" series, as per report from TV Guide.

"Geoff Johns, Andrew Kreisberg and myself designed the pilot and series to include Ronnie (aka Firestorm) -- and to actually have someone with Robbie's talent playing the role is beyond exciting," show executive producer Greg Berlanti said of Robbie's casting.

"I'm so excited to join forces with Greg Berlanti and The CW again on The Flash. Being brought into the DC Universe is a dream, I can't wait to get started!" Robbie Amell told Entertainment Weekly.

Robbie is playing Ronnie Raymond, who happens to be the human alter ego of the fiery superhero, according to the DC Comics where his character is based from.

"The Flash" stars "Glee" actor Grant Gustin as the titular role. Robbie, on the other hand, has been confirmed to have a recurring role in the freshman run of the show.

The ensemble cast of the series include: Danielle Panabaker, Carlos Valdes, Tom Cavanagh, Candice Patton, Rock Cosnett, Jess L. Martin, and John Wesley Shipp, among others.

Last time, when Robbie got cast as lead character Stephen for CW's newly cancelled fall offering "The Tomorrow People," the actor revealed that it was also his cousin Stephen, who was the first person to know about his casting.

"The Flash" is scheduled to premiere on Oct. 7, Tuesday, at 9/8c on The CW.

Check out the show's extended trailer below: