Celebrities have descended on Melbourne's Flemington Racecourse, all dressed up in their racing finest for this year's Derby Day.

There's plenty of money at stake as the action plays out on the course - but for most of us, it's all about what's going on trackside.

Derby Day is all about the monochrome, so as usual, it's a sea of white and black among A-list guests.

Leading the fashion pack was Myer ambassador Elyse Knowles, who looked incredible in an all-white ensemble.

The model wore a midriff-baring blazer dress, pairing it with strappy stilettos and a statement gold chain necklace.

The Block star sported a smoky eye, wearing her blonde hair out in beachy waves - perhaps a tribute to her new home, Byron Bay.

Glamorous WAG and races stalwart Nadia Bartel was one of the first to share her races-day look on social media.

Bartel, who split from AFL star husband Jimmy Bartel earlier this year, shared a video of herself in a white off-the-shoulder dress by Dion Lee with cut-out side panels and matching millinery.

"Derby ready so early this year," the mum-of-two and fashion influencer wrote in the caption.

"Excited to be hosting with (Studio 10) this morning."

Earlier this week, it was revealed that Bartel had landed an official role in Ten's Melbourne Cup Carnival coverage.

Bec Judd looked as stylish as ever in an Atoir dress, featuring a semi-sheer corset bodice, and paired with a white Prada handbag.

Also among the glamorous AFL WAGS in attendance was Jessie Murphy, a fashion blogger and the wife of Carlton Football captain Marc Murphy.

Murphy looked chic in a custom white dress by Cappellazzo Couture, which she paired with a wide-brimmed hat from Melissa Jackson.

While most birdcage attendees rocked either a black or white outfit, former foreign minister Julie Bishop was one of the few to wear both shades.

Bishop wore polka dot wide-legged pants with a white blouse, posing for photos inside the Myer marquee with long-term partner David Panton.

The Bach elor's Anna Heinrich posed in the Birdcage, showcasing her low-back white Forever New dress and elegant updo.

Meanwhile, fellow Bachelor alum Keira Maguire wore a simple black pantsuit with a netted fascinator.

Also rocking a black outfit was Myer ambassador Rachael Finch, with the model wearing a black jumpsuit and wide-brimmed hat.

AFL WAG Brit Davis opted for an all-white jumpsuit with a leopard print hat.

Earlier in the day, Heinrich and Maguire shared a sneak peek at their Derby Day prep on Instagram.