Zac Posen covers Heidi Klum's breasts in surprising topless shot Credit: Courtesy Heidi Klum

That's quite a job! Zac Posen became Heidi Klum's modesty saver on Thursday, July 31, by covering her breasts in a surprising topless photo the supermodel shared via Instagram.

Wearing nothing but a pair of pink panties, the Project Runway star, 41, seemed completely at ease as she struck a dramatic pose, only saved from her blushes by fashion designer Posen, 33, who held his left hand over her breast.

"I need something to wear for tonight's @projectrunway @lifetimetv" the German TV presenter captioned the bizarre picture which showed off every inch of her impressively toned body and muscular legs.

Mom-of-four Klum is no stranger to stripping down. Last summer the stunning model posed in a series of risque photos, one of which showed her hugging a palm tree in just her bikini bottoms, another making a face on her belly out of seashells and showing off the lower part of her breasts.

She later admitted she had some help taking the snaps—her mother!

"You will be surprised when you hear that my mom takes most of the photos," she told Access Hollywood in July. "I'm European. I don't like wearing tops. And I don't like tan lines."