Rosie McClelland has challenged fans to guess the sex of her cousin Sophia Grace Brownlee's Baby just a week after the latter announced her pregnancy.

"Omg this is so special, I'm gonna be an auntie....," McClelland, 16, wrote in an Instagram post on Oct. 29.

Her post was accompanied by a gallery of photos, one of which shows McClelland touching her cousin's baby bump. Another picture shows her with a shocked expression on her face as Brownlee, 19, laughs. As for the third photo, it shows the two posing before the camera.

She added in the caption, "So excited! What do you all think it will be? Sophia will reveal all next week so don't forget to subscribe to her YouTube!"

Fans gamely responded by making their guesses on the baby's sex in the post's comments section.

One of them said, "I'm so happy for both of you Sophia will be an amazing mum and youll be an amazing aunt! I think it'll be a boy!"

Another wrote, "I predict the baby will be a boy," while another commented, "Im thinking girl! Can see Sophia with a daughter."

The famous cousins went viral 11 years ago when they uploaded an adorable performance of Nicki Minaj's "Super Bass" on YouTube. The pair was later invited to perform on "The Ellen DeGeneres Show," and their guesting was highly rated by the audience. They later became regulars on the TV show and interviewed many celebrities in their segment called "Tea Time With Sophia Grace & Rosie."

Brownlee and McClelland reprised their "Super Bass" performance for the last time on "Ellen" in May.

"As a child, I always used to play dress up. So did me and Rosie. I was dressing up, and Rosie's favorite costume happened to be The Virgin Mary — you know, Mary and Jesus," Brownlee told DeGeneres before their performance.

She continued, "I was around and Rosie was wearing the outfit. I kept singing Nicki Minaj all the time and my Auntie, Rosie's mom, was the only one who had an iPhone. She said 'Why don't we film it? Rosie, quickly get out of the Virgin Mary outfit and get into that outfit.'"

The pair eventually wore matching pink lace dresses and tiaras in the video, which has since garnered 55 million views since 2011.

The duo has been active in their musical careers and released their latest singles and their accompanying music videos in May.

Sophia Grace Brownlee
Sophia Grace Brownlee, 10, is set to star in the movie musical "Into the Woods" alongside Meryl Streep and Johnny Depp. Above: Brownlee with her "hype girl" Rosie on "The Ellen DeGeneres Show." YouTube