Meet the reno rookies at the centre of 'biggest scandal The Block has ever seen'

Season 21 of The Block is about to burst onto screens with "the biggest scandal the show has ever seen".

In a brand new sneak peek, which you can watch above, we meet hairdressers, best mates and reno rookies Robby and Mat – and quickly learn to never underestimate a novice.

The Block Season 21 will premiere on Sunday July 27 at 7pm on Channel 9 and 9Now.

Robby and Mat introduce themselves to the crew as "a couple of hairdressers who have never done anything like this".

But whatever the pair may lack in renovation experience, they make up for in strategy.

"We obviously have a very big secret," Robby tells cameras.

READ MORE: All-important detail about The Block finally revealed

While we have no idea what secret the boys are hiding, it seems hosts Scott Cam and Shelley Craft do as they deliver some exciting news that has Mat making this face...

Both Robby and Mat are professional athletes, with backgrounds in football and figure skating respectively.

With that territory comes a common competitive streak and it looks like the boys will stop at nothing to win.

"We're about to take over The Block," they say.

"Game on moles."

WATCH: New season of The Block explodes with chaotic Scott Cam mix-up

What do we know about new Blockheads Robby and Mat?

Robby and Mat are just one out of five duos set to roll their sleeves up on The Block 2025.

The other Blockheads include couples Emma and Ben, Han and Can, Britt and Taz and Sonny and Alicia.

Robby and Mat met 15 years ago in Adelaide when Mat cut Robby's hair and they have been best friends ever since.

Robby and his partner Alyssa have been together for three years and recently welcomed a baby boy Brooks.

Robby, 37, is a very successful business owner and barber, with four salons under the Attaboy name in Adelaide. He also owns a café there.

Mat, 41, is known around the world for being a top hair stylist. He has a salon called MJ Hair and 32,300 followers on Instagram.

He's never watched an episode of The Block in his life but is ready for the challenge.

The Block Season 21 will premiere on Sunday July 27 at 7pm on Channel 9 and 9Now.

FOLLOW US ON WHATSAPP HERE: Stay across all the latest news from your favourite shows via our WhatsApp channel. No comments, no algorithm and nobody can see your private details.