Jennifer Morrison and Jesse Spencer at FOX 2007-2008 Programming Presentation at the Wollman Rink in Central Park, New York City, USA - 17.05.07

The ex-couple admits their upcoming kissing scenes in the medical drama were more than a little awkward.

And Morrison admits that the co-stars agreed not to actually lock lips until the kissing scene itself.

She says, "Out of respect, I saved it for the take."

But Aussie star Spencer admits the former couple's relationship woes helped in the tense scenes: "There's a different intensity now, but I think it really works."

Source: WENN