When Nicole Kidman took her co-star Alexander Skarsgard’s face in her hands and firmly planted a kiss on his lips as the crowd at the Emmy Awards watched on, her husband Keith Urban appeared unfazed.
But while he played the ever supportive partner for the cameras, later that night, Keith, 49, totally lost his cool.
Onlookers at an Emmy’s after party have revealed exclusively to Woman’s Day details of the couple’s explosive showdown.
Those at the awards celebration say they now fear for the couple’s marriage after what is being described as "a fight to end all fights."
"Keith had accused Nicole of disrespecting and humiliating him by kissing Alexander in front of everyone," our insider explains.
"They looked tense as soon as they walked into the after party and it was clear there was something going on despite their initial attempts to put on a united front."
WATCH: Nicole's acceptance speech for Best Actress in a Limited Series for Big Little Lies, post continues below...
"They’d posed for pictures on the red carpet outside, but they separated as soon as they got inside the party - with Keith going straight to the bar, tucking into the dumplings and pagodas which were being passed around."
"Meanwhile, Nicole made an instant beeline for Alexander despite Keith already accusing her of blatantly disregarding him."
"They were at loggerheads the whole evening and it looked like Nicole was trying to get under Keith’s skin – draping her arms around Alexander and trying to kiss him again, which was incredibly awkward for everyone else in the room."
"Keith and Nicole then had a heated discussion in the corner of the room, before both storming off relatively early in the proceedings," our source says.
For the full story on their explosive meltdown, get the new issue of Woman's Day - out now!