Attending the premier of their movie The Killing Of A Sacred Deer at the BFI London Film Festival. the once-chummy pair were nothing short of frosty towards each other, before becoming embroiled in what appeared to be a heated argument.
'There was definitely a lot of tension between Nicole and Colin on the red carpet, there's no denying that,' an onlooker said. 'They were whisper shouting at one another, and at one point, Nicole waved her hands about. Afterwards, they rushed off the red carpet together and we assumed they were having it out.'
After recently appearing in The Beguiled together, Colin and Nicole have formed a firm friendship having worked closely together for the best part of the year, leaving everyone - including Keith - wondering what on earth has happened to cause such a scene.
Evidence of growing tension between the famous pair has been unfolding in recent weeks, wth the duo's public appearances hinting that all is not well between them.
When asked about working with Nicole, 50, recently Colin, 41, refused to give the customary gushy response, abruptly dodging the question by saying: 'Next question.'
He has also described filming sex scenes with the Aussie star as 'awkward', and his recent experience filming alongside her as 'depressing.'
The two have also bickered with each other in front of the cameras on The Graham Norton Show and during an online video with a reporter from The Hollywood.
For the full story see this weeks issue of New Idea - out now.