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Saturday night chic! While attending a small birthday party for Kanye West at Ms. Lily's in New York on June 8, Beyonce stepped out in midriff-baring, skin-tight outfit.

PHOTOS: Kim and Kanye's romance

Continuing to put those pregnancy rumors to rest, the "Love on Top" singer rocked a black-and-white striped skirt and a matching cropped shirt with three-quarter length sleeves, showing off her toned abs. She finished the sexy look with a few accessories -- bold-colored orange heels, a black hat and black sunglasses.

Beyonce, 31, was joined by husband Jay-Z at the "Mercy" singer's 36th birthday dinner. Other guests included rapper Nas, Scott Disick (Kourtney Kardashian's beau) and Jonathan Cheban (Kim Kardashian's BFF).

Noticeably absent was West's girlfriend, Kim Kardashian, who is expecting their baby this July. But a source tells Us Weekly that, rest assured, her absence was not a sign of trouble for the couple.

PHOTOS: Kardashian family vacation album

"Kim isn't allowed to fly," the source confirmed to Us on Saturday, June 8.

Indeed, in a May 21 blog post, the "Keeping Up With the Kardashians" star explained that her visit to Paris was her "final trip" before the baby arrives.

"My final trip before I can't fly anymore!" she wrote, sharing pics from the vacay. "My mom and I flew to Paris to soak in the amazingness Paris has to offer before I can't travel anymore."

PHOTOS: Kardashian clan's Greek getaway

On Saturday, June 8, she made sure West was feeling the love, even from thousands of miles away while she was home in Los Angeles.

"Happy Birthday to my best friend, the love of my life, my soul!!!!" she wrote to him in an Instagram post, sharing a collage of photos. "I love you beyond words!"


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