The Battleship beauty landed the new role last year (14) and she admits she has always been a supporter of the sports organisation's events because they have helped her aunt Tara, now 40, engage with others facing similar intellectual disabilities.

Decker, 28, explains, "My aunt Tara, she was born with corpus callosum, which connects the left and right hemispheres of your brain and because of that, you develop mentally... I would say, now (she) is very much like a nine year old, that is the most fun, free-spirited nine-year-old you could ever know."

She adds, "It's a cause near and dear to my heart. I've seen it make a change in her life. Often times people with intellectual disabilities don't have something to go to. She doesn't have community friends and she doesn't have hobbies to do on her own, and Special Olympics provides that...

"I feel like when people are exposed to anyone with any disability, there's just an awareness they will not always have so Tara taught me that at a very young age."

Now Tara has also found a new sporting buddy in Decker's husband, retired tennis champ Andy Roddick - and it's left the blonde stunner a little jealous.

Decker jokes, "I think she worships my husband and loves him more than me, which is very frustrating because we grew up together and I think she would choose Andy over me any day! She's much more co-ordinated than I am so I let her and Andy take the tennis over for the family."

Decker, who recently took part in the Special Olympics torch relay, will be front and centre cheering on her aunt and her fellow athletes when the 2015 Special Olympics World Summer Games kick off in Los Angeles on Saturday (25Jul15).