The Plymouth centre-back was a brick wall at the back denying everything that came his way as the Pilgrims won 1-0.
Emotions were running high at Home Park for everyone and Katic got a little carried away in his post-match interview.
Speaking to ITV on their live broadcast, he answered his first question by saying: "I f****** love it."
He then said: "This is why I came here. it is good to get confidence of this win.
"We did good with the defensive structure and everybody gave their 100 per cent. We did what the coach asked from us. That is it."
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Host Mark Pougatch was forced to say sorry after the interview had ended.
He said: "Sorry about the industrial language, sometimes in the heat of the moment it all gets a little too much."
Katic was an absolute man-mountain in the heart of the Plymouth defence.
He made an incredible 11 headed clearances, the most by a player against Liverpool since Stefan Savic in 2020 in the Champions League.
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Incredibly, he also appeared to lose a tooth in a collision with his own teammate in the first half, but carried on playing.
Plymouth goalkeeper Conor Hazard said: "What a performance from him.
"He has made such a massive difference since coming in and we are lucky to have him."
The 28-year-old was making just his second appearance for the club since joining on loan from Zurich.
Katic was also one of Steven Gerrard's first signings as Rangers manager and helped them win the Scottish Premiership in 2021.
Teammate Hazard is also a former Celtic man, but it seems the two have quickly put rivalry aside.
Katic said: "First when I came here, I hated him because he was Celtic guy and I am a Rangers man. But I love him now."
The defeat for Liverpool ends their hopes of a quadruple against the side who are bottom of the Championship.
Mohamed Salah, Virgil van Dijk and Alexis Mac Allister were among those given the day off by Arne Slot.
Slot's gamble failed to pay off as Ryan Hardie's second-half spot-kick gave Plymouth a famous 1-0 win and sent them into the fifth round of the competition.