Tyson Fury strongly believes that his domestic rival, Anthony Joshua, made a mental decision to "quit" during his June 1 clash with Andy Ruiz.

Ruiz, pulling off one of the biggest upsets in boxing history, dropped Joshua four times for a TKO victory in the seventh round.

With the win, Ruiz captured Joshua's WBA, WBO, IBO and IBF world heavyweight titles - before a stunned crowd at Madison Square Garden in New York City.

Joshua was making his United States debut.

And now he exercised his right for an immediate rematch - which is being targeted for the fall.

But Fury feels Joshua had mentally checked out when he spit out his gum shield and wasn't giving off the appearance of a fighter who wanted to continue when the contest was waved off.

“It goes back to the same old thing, he gave up on himself,” Fury said to iFL TV.

“He didn’t get knocked out, he quit, he got jacked. He got put down twice, and he got up twice, but he didn’t show the referee that he wanted to continue. He spat his gum shield out and stood with his hands on the ropes.

“He quit. And when you quit once in your life, you’re finished. If you lose to a better man, everybody loses. Muhammad Ali lost. Everyone will lose to a better man. Not all good men will quit.”

Fury is not buying many of the conspiracy theories that people are claiming were responsible for Joshua's defeat.

“I don’t buy into it too much,” Fury said.

“When someone loses, the team always has to find a reason for why they lost. It can’t just be ‘oh, he was better than me’, there’s always a reason. Whether it’s the trainer, whether it’s the toe, whether it’s mental issues, family issues, whatever, there’s always be a reason as to why he lost.”