He's used to keeping himself in great shape after years as a top professional tennis player.
But now, sporting legend Mark Philippoussis is leaner than ever after taking part in the gruelling upcoming season of SAS Australia.
The 44-year-old took to Instagram on Tuesday to share a photo of the "aftermath" of his time on Channel 7's challenging reality TV show.
"Never been so excited to watch my ass get kicked!" Mark captioned the mirror selfie.
He showcased the physical toll his SAS stint has taken on his body, leaving his muscles toned and defined.
This is Mark's second reality TV appearance in the past year after he took part in the debut season of The Masked Singer in 2020. He was unmasked as the Echidna in the first episode.
Mark's fellow celebrity 'recruits' shared their praise and compliments for his transformation in the comments section.
"Absolute machine," wrote ex-footy star, Sam Burgess.
"Rigs of SAS calendar has started on [fire emoji]," said Home & Away's Dan Ewing.
"SAS - Super Ab Solutions!" chief instructor Ollie Otterton added.
One curious fan asked Mark just how much weight he'd lost while on the show, which sees contestants put through their paces by elite ex-Special Forces soldiers Ant Middleton, Mark 'Billy' Billingham, Jason 'Foxy' Fox.
"Just over 6 kg," he replied.
Season one star Shannan Ponton revealed he'd lost 5kg and suffered a bout of hypothermia after jumping into a freezing lake.
Days earlier, the list of 18 famous faces who will be taking part in the upcoming season of SAS Australia was unveiled.
Here's the full line-up:
Alicia Molik – Tennis Champion
Bonnie Anderson – Singer / Actor
Brynne Edelsten – Socialite
Dan Ewing – Actor
Emma Husar – Former Politician
Erin Holland – TV Presenter
Heath Shaw – AFL Star
Isabelle Cornish – Actor
Jana Pittman – Dual Olympian
Jessica Peris – Sprinter
Jett Kenny – Ironman
John Steffensen – Olympic Runner
Kerri Pottharst – Beach Volleyball Olympian
Koby Abberton – Bra Boy
Manu Feildel – Celebrity Chef
Mark Philippoussis – Tennis Legend
Pete Murray – Singer-Songwriter
Sam Burgess – NRL Star
Never miss a thing. Sign up to Yahoo Lifestyle’s daily newsletter.
Or if you have a story idea, email us at firstname.lastname@example.org.