The 27-year-old Arsenal ace scored directly from a corner in what was Republic of Ireland's first ever goal at the Women's World Cup and soon she was trending on Twitter.
Her in swinging corner from the right in the fourth minute eluded everyone as goalkeeper Kailen Sheridan failed to claw away the curler.
McCabe's delivery ultimately smashed off the post before nestling into the back of the net to spark jubliant scenes at the Perth Rectangular Stadium.
A delighted McGregor led the applause for the Arsenal star on social media, as the UFC legend tweeted: "Iconic moment in Irish football just now!
"The ladies running the show! Scored from the corner WOW! Captain McCabe!"
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He followed that up by simply stating: "What a player!"
Meanwhile, former talkSPORT host Laura Woods simply posted: "KATIE MCCABLE! Wallop."
And it wasn't just Woodsy and McGregor in awe.
Social media was sent into meltdown, as one Twitter user said: "Katie McCabe is something else from a dead ball situation, wow."
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Another posted: "Omg the gasp i just let out!! Katie Mccabe that was unbelievable!"
A third added: "Katie McCabe adding another amazing goal to her compilation."
This fan then messaged: "What's actually incredible about that Katie McCabe goal is not only did she mean it, but she knew as soon as she hit it. Amazing."
Meanwhile another simply stated: "Katie McCabe you absolute legend!"
It was McCabe's 19th international goal for The Girls in Green on her 75th appearance.