Diehard Swifites will likely remember this well ... back in 2011 -- on the heels of Taylor releasing her OG 'Speak Now' album -- she went on tour at the young age of 21 ... when she had essentially reached pop star status and her fame was absolutely skyrocketing.

Along the way, she stopped off in St. Louis for one of her shows ... and during her performance, a gust of wind shot up onstage and started taking her blue dress with it.

Taylor was able to get a handle on things before it became too embarrassing ... and she played it off like a pro, getting right back to singing/acting like nothing had happened. This moment -- which went viral at the time -- was captured on video ... albeit, from the back.

Yes, her undies flashed a bit -- but her quick hands managed to avoid exposing her frontside ... which was actually captured by a (longtime) front row fan at the time, who snapped what can only be described as an iconic shot, especially when you see how it sizes up to Marilyn.

TMZ has obtained the photo ... and it's truly something to behold, in a good way of course. The image is a little fuzzy, but hey -- the technology back then was what it was, y'all.

Anyway, as you can see ... she's bent forward, with her left hand covering the dress and the mic in the other hand. Indeed, her pose here is just like the one MM struck in 'The Seven Year Itch' -- when she stood over a subway grate and a gust of wind shot up into her outfit.

The resemblance of the two frames is uncanny -- and considering how big Taylor has gone on to be ... you could maybe even argue it was destiny, seeing how it happened naturally.

The best part of revisiting this time is that Taylor is actually on the verge of re-releasing 'Speak Now' (Taylor's Version) some 13 years later ... so, it marks an anniversary of sorts!