Sydney brother-sister duo *Grace *and *Joseph Caristo *hoped to fly under the radar on *The Amazing Race Australia *.
But, as tonight's tense episode of the globe-trekking series reveals, the siblings, pictured right, have done anything but that.
What started off as playful banter between Grace, 21, and do-or-die Victorian *Paul Montgomery *, turned into a running clash between the two.
And things go to extremes tonight when Montgomery becomes physical against Caristo.
But as Grace explained to _AAA _last week, the light-hearted taunts she made when the pair crossed paths in Dubai were meant as a "bit of fun."
"The thing is, when you're racing you don't actually know what kind of people you're up against," she said. "And because Paul was so much ahead of us we didn't really know what type of person he was. We had absolutely no interaction with Paul and *Steve *( *Scale *) and it wasn't until we hit Dubai where we actually had time to cross paths."
Grace said she didn't realise how badly the serious Victorian would react to her comments.
"That's when he started to pick on me and I guess that's where I felt like a victim to his, like, ultra-competitive behaviour," she said. "At that point, Joe and I realised that we didn't really want to step on his toes because he can be quite threatening and what we really wanted to do was to stay under the radar."
But the trouble continued in Turkey, sparking further tensions between the two teams.
"I think the problem was, he was the type of person to have personal issues back when he was young and he was picked on a lot so when he entered adulthood he had these issues that haven't been treated, which I guess he's dealing with today," Grace said.
Joseph, 22, said he was really quite "furious" with what had unfolded and didn't have any qualms about confronting Paul.
The pair also told _AAA _ they had made no effort to make amends with Paul during the remaining legs of the race.
See the heated exchange on The Amazing Race Australia at 7.30pm today on Seven/GWN7.
' Joe and I realised that we didn't really want to step on his toes because he can be quite threatening and what we really wanted to do was stay under the radar.'