Carrie Underwood Geeks Out Over Singing Happy Birthday to NKOTB's Danny Wood and Jordan Knight

Marcello Ambriz

Carrie Underwood is geeking out over the New Kids on the Block!

The country star had a total fangirl moment after singing "Happy Birthday" to NKOTB members Jordan Knight and Danny Wood during the group's Total Package Tour stop in Nashville, Tennessee, on Wednesday.

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The clearly surreal stage experience left Underwood in shock.

"Um...did I just sing happy birthday to @dannywood and @jordanknight on stage with the NEW KIDS ON THE BLOCK?!?! Yup!" she excitedly tweeted.

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The 34-year-old GRAMMY winner also shared a photo with NKOTB on Instagram and videos from the concert.

"I'm instantly back in the 6th grade," Underwood jokingly wrote.

And she’s not the only American Idol alum to perform in Nashville this week. Kelly Clarkson showed support for Underwood’s husband, Mike Fisher’s, team during the Nashville Predators' Stanley Cup playoff game against the Anaheim Ducks on Thursday. The "Piece by Piece" singer rocked a Predators jersey as she belted out the National Anthem just ahead of the hockey match.

Earlier in the month, Underwood cheered on her hubby as he helped his team defeat the St. Louis Blues in game four of the Western Conference second round series.

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