Unified heavyweight world titlist Andy Ruiz Jr. was due to begin training for his rematch with Anthony Joshua on Monday, but those plans did not come about, trainer Manny Robles told ESPN on Monday night.

“We’re working on getting back together this week. I was hoping it would be [Monday] but it wasn’t, so we’re definitely working on that right now,” Robles said. “We didn’t have a training session [Monday], but we’re scheduled to start training this week.”

Ruiz scored a massive upset when he knocked out Joshua to take his three major world title belts on June 1 at Madison Square Garden in New York. Ruiz (33-1, 22 KOs), 29, of Imperial, California, survived a third-round knockdown to drop Joshua (22-1, 21 KOs), 29, of England, twice later in the round and then scored two more knockdowns in the seventh round to score a knockout.

Joshua quickly exercised his contractual right to an immediate rematch and recently his promoter, Eddie Hearn of Matchroom Boxing, announced that the fight would take place on Dec. 7 at a soon-to-be-constructed outdoor stadium in Diriyah, Saudi Arabia, where the government is backing a site fee worth tens of millions of dollars.

Ruiz, however, has not committed to fighting in Saudi Arabia over security concerns, even though Joshua and Hearn contractually have the right to determine the date and location of the rematch.

Still, Robles said that is not his concern. His job is to get Ruiz ready for the fight, wherever it takes place.

“We have to figure out if I should drive over to Imperial and get things going there or if he’ll come to [Los Angeles],” Robles said. “We might start training here in L.A. and then move our training to either Big Bear [Lake, California] or maybe somewhere in Mexico, maybe the Otomi [a mountainous region outside of Mexico City] or maybe the mountains in Jalisco, but definitely in the mountains, at altitude.

“We’ll get things going. We got more than enough time to get ready for December.”

Robles said that, like Ruiz, he would prefer for the fight to take place in the United States.

“If I could make the decision as far as where the fight would be I would say here in L.A. or [Las] Vegas, but it’s not up to me,” Robles said. “It’s up to the promoters, Mr. Eddie Hearn and [Ruiz adviser] Al Haymon to sit down and decide where and when. That has absolutely nothing to do with me. My job is just to get the fighter ready.

“But the first fight was in New York and the second fight was supposed to be in New York, or in England or Wales. But now all of a sudden it’s in Saudi Arabia, which I’m not 100 percent sold on. But it is what it is. Like I said, my job is to get my guy ready and soon as I have him back in the gym I’ll be able to make an assessment as to where he is physically, mentally, and then take it from there.”

Robles said he has kept in touch with Ruiz and seen him a few times since their historical victory.

“He’s not in great shape, but he’s hitting the gym back home in Imperial. He’s running the treadmill, but obviously we haven’t fully begun training camp,” Robles said.

“Once we do we have [close to] four months to get ready for a fight. That’s enough time to get him in shape. Let’s hope we can get him back in the gym real soon and get him going again.

As for Saudi Arabia, Robles said there are questions that have been asked of Hearn regarding safety and security.

“Obviously, we have questions about the commission and who will oversee the fight since we understand there’s no athletic commission there,” he said. “We want to know about drug testing. So these are simple questions that deserve answers. We shall see.”