A South Korean bride has become a viral sensation after she stunned her husband on their wedding day with a jaw-dropping vocal performance of K-pop star IU's "Good Day."

When the Russian musician Anna Yuna, who has more than 50,000 followers on Instagram, sang the technically ambitious song at her reception, her powerhouse performance and control left guests slack-jawed.

Her cover has since gone viral on Threads and other platforms, with fans comparing her to IU herself.

"Good Day," originally released in 2010 as the lead single from IU's album Real, is known for its bright tone and especially challenging high notes, which require expert-level breath control and vocal range.

Despite the difficulty, Anna Yuna "nailed every note," including the song's iconic three-note high climax — a section that has become a vocal benchmark in the K-pop world.

Guests were so impressed that they reportedly chanted "IU! IU!" after the bride's performance, highlighting the uncanny similarity between the two voices.

"She sounds just like her!" one guest can be heard shouting in a clip posted online.

IU, often referred to as an "idol of idols," has been recognized throughout her 17-year career for her unique tone and emotional delivery.

While fans agree IU remains in a league of her own, many praised Anna Yuna's performance as a fitting tribute to the singer's artistry.

Yuna is often seen doing covers, as well as uploading personal and musical posts on her Instagram.

Her viral moment has also drawn attention from K-pop fans, some of whom wonder if she will explore other types of professional prospects within the music world.

As of Thursday, the performance continues to trend across social media, with many dubbing it "the most iconic wedding moment of the year."