Guess who! Iconic US pop star makes shock appearance at Derby Day in Melbourne

American pop star Anastacia made a rare appearance at Derby Day on Saturday.

The Left Outside Alone singer, 56, looked sensational as moved among the crowd gathered at Flemington Racecourse for the first event in Melbourne Cup week.

Showing no signs of her well-publicised health dramas, Anastacia looked radiant in a stunning outfit that consisted of a lace dress with plunging bodice top and an edgy rhinestone leather jacket.

Letting her long blonde locks fall over her shoulders, the ageless performer capped off her look with a tiny black feathered race day bonnet and a pair of tinted glasses.

For accessories, Anastacia wore a set of hooped earrings and a chain necklace with a musical note motif.

She also sported an elaborate silver ring ornament on one finger and flaunted a fresh manicure.

For footwear, the hitmaker chose to wear a set of black chunky boots.

She became a household name in 2000 with the release of her smash hit single I'm Outta Love, only to disappear from the charts in recent years.

Three years ago, Anastacia revealed how various health problems made it nearly impossible for her to maintain a global career over the years, having battled illnesses including Crohn's disease, a heart condition and two bouts of breast cancer.

'That's probably been my biggest problem – when I'm really ready and raring to go, another disease comes,' Anastacia told News Corp a day after she was crowned the winner of The Masked Singer Australia in 2021.

'It's been tough to be able to keep the motion and momentum going,' the pop star added.

The Sick And Tired songstress was diagnosed at 13 with Crohn's disease, an inflammatory bowel disease that can cause severe chronic symptoms that never go away.

She was also diagnosed with breast cancer in 2003, and not long after was also diagnosed with supraventricular tachycardia - a heart condition with causes varied and rapid heartbeats.

After being diagnosed with breast cancer for a second time in 2013, Anastacia decided to undergo an immediate double mastectomy.

Last year, Anastacia appeared on the French version of The Masked Singer and released her eighth studio album Our Song which soared to the top of the charts in Germany and the UK.