Oliver Queen and John Diggle might team up for a new mission in 'Arrow' Season 4.Facebook/Arrow

"Arrow" fans are likely to see character changes for Oliver Queen (Stephen Amell), Laurel Lance aka Black Canary (Katie Cassidy), John Diggle (David Ramsey), Thea Queen (Willa Holland) and Roy Harper aka Arsenal (Colton Haynes).

As the billionaire playboy and his lady love Felicity Smoak (Emily Bett Rickards) return to Starling City, they will have new challenges to face.

Since Quentin Lance (Paul Blackthorne) and his team believe that the vigilante archer died during a prison riot, it will be difficult for the protagonist to protect the city without revealing his identity. Although Amell teased a costume change for his character, he could still be the prime suspect.

Fan speculations suggest that Oliver could take the help of a double, who could appear in the public while he saves the city. "He could use a robot, hologram, clone, alternate-version-of-himself-from-another-dimension, or ventriloquism", wrote a viewer on Reedit.

Recently, Amell also teased a few unexpected changes in the fourth season of The CW series.

"It still feels like our show but there are different elements that I think people are going to enjoy. We get to see some characters interact that weren't always the closest of friends or interacting on a regular basis which is neat when you're doing new stuff in the fourth season of a show," he told TV Junkies.

So, there is a buzz that Diggle could play the Guardian in a metallic blue and black costume with a yellow helmet mainly because Ramsey stated that he will have a hero costume in season 4, stated Movie Pilot.

The CW will air the premiere episode of "Arrow" season 4 on Wednesday, 7 October, at 8pm.