The subtle sign Nicole Kidman is set to flee to Australia, amid her shock divorce from Keith Urban

Nicole Kidman has been spotted being comforted by sister Antonia, sparking rumours the Oscar winner could be set to flee to her beloved Australia in the wake of her divorce.

Kidman, who grew-up in Sydney, chatted with her sister on a walking trail near her multimillion-dollar Nashville mansion, which she shared with Urban and their two children, Sunday Rose, 17, and Faith Margaret.

The Moulin Rouge! Actress went incognito in dark leggings and an athletic jacket during the outing. She also wore a baseball hat and black sunglasses for the hike, as they chatted together.

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Kidman is clearly leaning on her Sydney-based sister Antonia, during this difficult time, with many celebrity watchers wondering if she will follow her sister back to the Harbour city.

“Nicole’s sister [Antonia] has been a rock, and the entire Kidman family has come together to support one another,” a source told US People magazine, after photos were published.

Nicole and Antonia are known to have a close bond, with the pair regularly spotted at swanky awards shows together.

Kidman regularly returns to Sydney for family engagements and private downtime.

She famously owns multiple apartments in Sydney’s Milson’s Point and a 45-acre rural property called Bunya Hill in the Southern Highlands, which could provide ample privacy for her.

Nicole Kidman has been comforted by sister Antonia, following her split from Keith Urban. Credit: Taylor Hill/WireImageSydney-based Antonia Kidman. Credit: Don Arnold/WireImage

Kidman is believed to have floated the idea of moving back to Australia last year, following the death of her beloved mother, Janelle, in September.

Kidman’s father, a Sydney academic, died of a heart attack in 2014.

The Oscar winner filed for divorce earlier this week, citing “irreconcilable differences” for her grounds of divorce, in paperwork lodged in Davidson County.

Nicole will be considered the “primary” parent for the girls. Keith is listed as having parenting time from Saturday 10am to Sunday, 6pm, every other weekend.

Speculation is growing about the reason for the split.

Kidman was previously married to Tom Cruise, 63, from 1990 to 2001. They adopted two children during their union.

The Australian actress tied-the-knot with Urban at the Cardinal Cerretti Memorial Chapel in the grounds of St Patrick’s Estate, Manly, in Sydney, back in 2006.

The couple first met at G’Day LA, a Hollywood event promoting Australia, in January 2005, and they began dating six months later.