TYSON FURY fired a shot at Anthony Joshua by goading that his rival was "supposed to come train with us".
Unified champion Joshua, 30, offered to spar Fury, 32, before the Gypsy King challenged Deontay Wilder.
But the proposal was never followed up.
It mattered little as Fury dominated Wilder, 34, last February to win the WBC belt and set up an undisputed title decider against AJ.
The heavyweight champions have verbally agreed to a two-fight deal for 2021 - and Joshua was reminded about his no-show in sparring.
Fury told Behind the Gloves: "Anthony Joshua says a lot.
"He was suppose to come into training camp and train with us, I guess that goes to show how far his word goes.
"We wanted some of that action.
"He said he was coming, but he didn’t. We can’t really take what he says as his word anymore."
Before the pair can settle the score in the ring, they both have unwanted interim fights to first handle.
oshua faces Kubrat Pulev, 39, in a mandatory title defence in December.
And Fury is signed to an immediate rematch against Wilder, targeted for the same month.
Joshua warned the Battle of Britain has to materialise sooner rather than later, having urged the Gypsy King to contemplate retirement.
Fury fired back by challenging AJ to do the job himself.
He said: "If I’m too old in the tooth and I need to retire, come and retire me."