The sledge came as the 48-year-old Today host was interviewing NRL chairman Peter V'landys about the NRL Grand Final.
Peter poked fun at Karl, saying, "I'm told that there's also maybe another event happening on that day. Maybe there's a fight between you and Gallen. Is that is that on still or?" referencing rugby league player-turned-pro boxer Paul Gallen, who has previously challenged Karl to a fight in the ring.
"It's all about this with Paul Gallen. Blah, blah, blah," Karl responded, making talking signs with his hands.
Peter then advised Karl not to take on the fight before bringing Kochie into the mix.
"It's like a lion against a kitten!" he joked, adding, "If you want a couple of easy fights, fight David Koch. Fight Kochie first, then work your way up to Gallen!"
Karl then responded, "He's hopeless! He's hopeless! Couldn't handle himself in the ring that's for sure."
It's not the first time the rival hosts have jokingly hit out at each other, with Kochie sharing a hilarious photo of Karl to Instagram earlier this month while both shows were broadcasting from London following the Queen's death.
Kochie shared photos of the crowd watching the Queen's procession and then posted a photo of Karl behind a fence looking at Kochie, with his hands wrapped around the bars.
"Gotta keep the rif-raf out," Kochie captioned the image as he tagged Karl.
The Today host clearly appreciated the jab, sharing the snap on his own Instagram Stories.
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