Olivia Culpo, one of Sports Illustrated Swimsuit Issue’s 2020 cover girls, is revealing what it really takes to get those hot shots.

“My knees were bleeding from the rocks, and I was being taken out by waves,” said the social media superstar, 28, of the marathon shoot days on location in Bali with longtime SI photographer Yu Tsai.

“We have to wake up at 4 a.m. to get the right light, and we shoot until the sun goes down.”

Culpo called the shoots with the mag “inspiring” and “exhilarating.”

“You have to dedicate a lot of time, energy, and mental focus into what you want to happen,” she said.

Indeed, she stuck to “low-carb, high-protein, and high-fiber” diet ahead of her shoots — though she loves to splurge on junk food like fried chicken with boyfriend Christian McCaffrey, whose family residence in Colorado has served as her home base throughout the COVID-19 crisis.

“We’ve been together the entire time, and it was the most time we’ve been able to spend together,” Culpo told us of her ball-playing beau, 24; he’s even had to step in as her in-house shutterbug, snapping the pics for her latest Vogue India cover.

“That was really challenging,” she admitted. “I definitely have a very specific vision in any photo I take. It was a lot of teamwork to find the right light, clothes, and backdrop. I had to have a heavy hand in the creative direction.”

And as for the slinky suits Culpo modeled for this year’s SI Swim issue, on stands July 21? Some of them are almost too sexy to show off.

Said the star: “Some of these bikinis you couldn’t really wear in public.”