The British heavyweight’s career hangs in the balance after his shock defeat to the Mexican nearly six months ago.
Like in the first fight, AJ is the bookies favourite to come out on top.
And Ruiz reckons the weight of expectation is firmly on the Watford lad.
"I think right now he's pressured, he's more focused on getting the belts back,” he told iFL TV .
"I think he's worried about getting the belts back.
"But I think he's in it to win it.
"He wouldn't have picked this fight for nothing.
"Hopefully he brings it December 7 because I'm going to do whatever it takes to retain those belts and bring them back over here."
American heavyweight Deontay Wilder admitted earlier this week that he’s now more likely to fight Ruiz than AJ now.
“With Joshua, we tried many times to get that fight unfold and make a dream fight happen, you know for the fans to unify the division,” he said.
“To have one champion, one face, one name.
“As you can see that was a long process, a process where we had different markers being stretched.
“Once we completed, we had to do something else, we had to do this, we had to do that. It was a lot.
“This is a gladiator’s sport, this is a man’s sport and I’m a grown man and I don’t have time for games.
“Being that Ruiz is under the same stable as I, a much easier fight to make, and I think an even more exciting fight as well.”
Wilder has his own rematch to deal with first.
The Bronze Bomber will fight Luis Ortiz in Las Vegas on November 23.