ITV show 'Splash!' sees the Olympic medallist coach celebrities to learn to dive, and The Sun reports that the Argentinian model will be one for the celebs taking part, along with former Olympic ski jumper Eddie 'The Eagle' Edwards.
Leandro, who split from Katie in October after dating for around a year-and-a-half, has apparently been spotted training at an Essex pool.
Tom also posted a picture online of himself and Leandro, saying: "Fun night last night with mi amigo."
But Katie is rumoured to be worried about what Leandro will reveal about their relationship on the show.
Following their split, Leandro gave an interview saying: "I left her simply because she is crazy. Katie's brain is not wired right, or the wires don't connect properly.
"I don't know what's wrong with her. I was thinking it over recently and one day decided to pack my bags and leave."