Deontay Wilder has called on Tyson Fury to "honour his agreement" for a third fight.
Earlier this week, Fury said Wilder will "never get a shot" after the American accused him of putting "something hard" in his gloves before their February bout.
Fury beat Wilder in Las Vegas to win the WBC world heavyweight title, 14 months on from them fighting to a draw.
"It is time for you to be a man and give me my shot," he said.
The 35-year-old added on Twitter: "The only thing I want from you is for you to honour your agreement and fight me.
"I gave you two shots when I didn't have to and it changed your life."
A trilogy fight was due to take place during the summer but delays have led Fury, 32, to seek other plans and state their rematch clause has lapsed.
Their third bout was slated for July and later aimed at October before plans emerged for a December fight in the US, which Fury later said Wilder's camp had tried to push back into 2021.
"He will never get a shot at me now. Finished," Fury told boxing journalist Gareth A Davies on Monday.
"For what he has said. Losing is one thing. I don't even want to give him any air time. That's it for him."
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