Jake Paul claimed KSI is "afraid to sign the contract" to seal a fiercely anticipated bout between the pair.
The two YouTube stars turned boxers are widely expected to bring their rivalry to a head in the ring after regularly exchanging blows on social media.
Paul suffered a first career defeat last month in a split decision loss against Tommy Fury, with KSI posting a video mocking the result and calling both fighters "trash".
While Paul's immediate priority is a rematch with Fury to avenge his defeat, a clash with KSI remains in his sights, but he has accused his rival of being scared to commit to terms.
"Talk is cheap, because with all that talk and whatever he said, he's still afraid to sign the contract," Paul said on the Impaulsive podcast.
"He can talk all that s***, but let's get in the ring, 100 per cent. Talk that s***, let's sell some f***ing pay-per-views brother.
"All things considered, I talk a lot of s***, but I back to back to back I schedule these fights and go in the ring and do them, whoever it is, anywhere, anytime, any place.
"I've backed it up and proven that and shown it. He's hot on Twitter, he's got the Twitter fingers, but when it comes to actually fighting me, you have been gone, absent, haven’t actually shown up or signed the contract.
"So, talk is cheap and let's just hope he gets into the ring and we can settle all of the s*** talk there, after I go back and avenge this loss with Tommy Fury.
"I'm KSI's end goal, but for me there's bigger fights out there, it's just a pit stop."
Don’t judge me by my wins, judge me by my losses. Congrats to Tommy, his team and his family. Thank you to everyone that tuned in. Saudi Arabia thank you as well. I will be back.— Jake Paul (@jakepaul) February 27, 2023