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Kelly Rowland admits the constant comparisons to Beyonce Knowles Carter, were "Torture."

Kelly, who was rumored to be Beyonce's half-sister, said Beyonce continues to rent space in her head.

"Can you imagine what it's like being in a group with Beyonce?" she asked a Voice Australia contestant.

The Destiny's Child singer said she tortured herself because she didn't measure up to DC's leggy blonde lead singer.

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Speaking candidly about her life-long relationship with Bey, the 39-year-old Aquarius said she was intimated by Beyonce, also 39, because she thought of herself as an ugly duckling.

The moment of self-reflection occurred when Voice Australia Contestant Chris Sebastian said he was concerned about being outshined by his brother, Australian Idol winner Guy Sebastian.

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"I know this feeling," said Kelly, pictured far left with Farah Franklin, Beyonce and Michelle Williams. "Can you imagine what it's like being in a group with Beyonce? I would torture myself in my head."

Kelly said the brutal self-comparisons to Beyonce impacted her career and hurt her feelings of self-worth.

"I would be lying if I said no, it's never bothered me. That's bull. There was a whole decade, if I am being completely honest, a decade, where it was like the elephant in the room. It was the thing that would constantly be on my shoulder."

Beyonce Knowles, Kelly Rowland

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The mom-of-one said she struggled all her life to keep up with Beyonce, who had No. 1 hit singles after she left the group.

She said Beyonce's dominance on the charts caused her to rethink every step she took in her career - right down to her wardrobe.

Kelly said picking out her wardrobe was a chore because she would think: "'I can't wear this dress because they're going to say it's like B.' Or, 'I can't have a song like that because it sounds too much like B.'"

Kelly has never had a No. 1 hit single outside of Destiny's Child.