If you throw a heap of genetically blessed teenagers into a house together, then pose them up in photo shoots titled "sexual chemistry", the fireworks are sure to spark. As is revealed on the Channel Seven catwalk catfight series tonight, when Sydney model Hannah McCarthy steams up the screen with glamour boy Rhys Uhlich in the seriously sizzling sexual chemistry fashion shoot.

While all the female model contenders were hoping to be paired with hot favourite Uhlich, brunette beauty McCarthy resembled the cat who got the cream when producers selected her to star.

And although there's nothing quite like being instructed to play out a compromising position with a preened and buffed chiselled-jawed babe, McCarthy had to restrain her affections - she has a devoted boyfriend outside the show.

But will their relationship go the distance?

"As much as Hannah talks about her boyfriend non-stop, I tell you what, if Rhys was willing to give her a bar of it, I'm pretty sure James (her boyfriend) would be out the window," fellow MMAS finalist Luke quipped.

We're not sure what Rhys's girlfriend would think of such talk.

By Sarah Grant