Normani Kordei Delivers Love Letter to Hometown of New Orleans in Emotional 'DWTS' Semi-Finals Dance

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Normani Kordei
paid tribute to her hometown of New Orleans with a flawless jazz routine on Monday's Dancing With the Stars semi-finals, but it was her grandmother, Barbara, that really stole the show.

The Fifth Harmony singer
opened up about some of the more emotionally challenging aspects of her childhood, including her mom's diagnosis with breast cancer when Kordei was only five years old, and living through Hurricane Katrina in 2005, which damaged her home and displaced her from everything she'd grown up with.

Normani, her parents and her grandmother moved to Houston in the wake of the disaster, and she continued to pursue her passion for singing, supported by her family -- especially her grandma -- every step of the way.

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"Deep down, I am still that little girl sitting down on the couch watching Dancing With the Stars with my grandmother," she reflected.

The 20-year-old pop star dedicated her dance with partner Val Chmerkovskiy to her loved ones, her friends and the city she knew as her childhood home, the Big Easy.

Kordei and Chmerkovskiy took the stage for a jaw-dropping jazz routine set to an up-tempo rendition of the Louis Armstrong classic "What a Wonderful World," and from the first moments of the performance, it was clear that the pair were in total control of the dance floor.

The set was made up to look like Bourbon Street in the middle of New Orleans' famous French Quarter, and Kordei dominated the number in a stunning, fringe-covered purple number. Her effortless chemistry with Chmerkovskiy was in top form and there was no doubt from the audience reaction that it was certainly the performance of the night.

WATCH: Normani Kordei Opens Up About Fifth Harmony Joining Her Onstage for 'DWTS' Performance

After the routine, Chmerkovskiy and Kordei came up to her grandma, who was sitting in the audience, and the handsome pro dancer gave her something to really remember -- a sweet kiss full on the lips.

As for the judge's feedback, it was every bit as effusive as the audience's, and all four absolutely loved the number. Len Goodman, one of the singer's most strict and harsh scorers, even gave her a standing ovation, and the duo walked away with a perfect 40 out of 40.

Barbara joined her granddaughter and her partner on the balcony with Erin Andrews as they got their scores, and the feisty grandma declared that she was the one who kissed Chmerkovskiy, adding, "It was awesome," and then planted another one right on his mouth.

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Kordei's grandma also opened up about what it's been like to watch the young singer dancing her heart out each week, sharing, "It's a dream come true. My only little girl, now she's my big girl… baby, I'm so proud of you."

Earlier in the evening, Kordei and Chmerkovskiy performed a dance especially selected for them by Goodman. The pair performed a film noir-themed Viennese waltz set to Rihanna's "Desperado," and blew the house down with the sultry number and passionate choreography. The twosome earned a score of 36 out of 40 for the performance.

ET caught up with Chmerkovskiy before this week's emotional episode and the pro opened up about Kordei's powerful jazz dance. Check out the video below to hear more.

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