SINGAPORE - Captain America star Chris Evans appeared to have slipped up on the Internet on Sunday morning (Sept 13), when he posted private photos onto his Instagram stories - including an explicit picture.

The 39-year-old actor shared a screen recording of his friends playing the trivia game Heads Up!, but when the video ended, the camera roll with the explicit image was displayed on the screen.

Among the thumbnails of photos was one that appeared to contain male genitals and a meme of himself with the text "Guard that p***y."

The Instagram story was immediately removed, but not before screenshots were taken and widely shared.

"Chris Evans" is also trending on Twitter.

However, fans of the Avengers super star have come to his rescue, asking people to respect his privacy and refrain from sharing the image.

They are also flooding Twitter with wholesome content - such as pictures of Evans and his dog Dodger - to drown out the explicit pictures.

American entertainment website PopCulture.com said that some fans are speculating that the NSFW (not safe for work) picture might be that of Evans' younger brother, Scott, whose nude photos have been leaked in the past.

It is unclear if the camera roll is Chris Evans' or not, and he has yet to address the leak publicly.

His Avengers co-star Mark Ruffalo, however, has weighed in on the slip up on Twitter, writing "Bro, while Trump is in office there is NOTHING you could possibly do to embarrass yourself. See... silver lining."