Andy Ruiz Jr lost his world belts back to Anthony Joshua on Saturday night.

Ruiz was thoroughly outclassed by Joshua as the Englishman won by unanimous decision.

The Mexican fighter felt the need to apologise to his family and training for his poor preparation ahead of the bout.

"Me and my dad and my team have been talking, that I should have listened to them," Ruiz Jr said in his post-fight conference.

"I shouldn't have put on all this weight. I tried to kind of do the training on my own you know and [turning to trainer Robles] I'm sorry Manny, and I'm sorry to my dad. I should have listened to them more".

His father has now given a brutally honest interview detailing just how bad his camp was.

“Andy thought he was going to do good in the weight in the fight,” Andy Ruiz Sr told Boxing Social, per BoxingNews24.

“I told him a month ago that ‘you’re not going to do good at the weight. It’s going to be too hard, because you’re going to be tired, and you’re not going to have the movement. You have to lose the weight.’

"He came overweight, that was the problem. It was too much weight for his body. There was no way he was going to do something good, so now he’s learned his lesson.

“I told him, ‘You have to lose weight.' He was not listening because of the fame. He was with a Rolls Royce, he was with his friends, he was throwing parties, and not listening to the camp."

Ruiz Sr also revealed how his son was training by himself and described it as the 'worst camp he could be doing'.

“He was running by himself. We were in a house in Manhattan Beach, that we he could come with us, and stay in the house,” Ruiz Sr continued.

“He didn’t want to stay with us. He wanted to stay with his friend, and try to run by himself. It was the worst camp that he could be doing. He didn’t do the right things."

Ruiz Sr expressed his belief that his son couldn't throw punches because of his weight.

“You seen the other fight, he threw 10 punches, 11 punches,” said Ruiz Sr. “Now he was just throwing the jab to the body, the right hand. He didn’t throw any combinations, because he wasn’t right with the arms, and the legs."

And Ruiz Jr has promised his father he will listen to him ahead of his next fight.

"He’s disappointed, and he said, ‘I should have listened to you, and Manny Robles. I never listened, and I tried to train by myself, and do the thing by myself.

"It didn’t work, because I didn’t listen. It’s all my fault. Now it’s going to be different, because all his friends are going to kick him out.

“We’re going to make a good camp, and get a good physical trainer. We didn’t get a good physical trainer. He was doing all the training by himself. I told him, ‘We have to get a good physical trainer,’ but he didn’t listen to me.

"Now that he knows that he needs it, he’s going to listen to me, and get a good physical trainer, and go down to 255. That’s the weight that he had to be, and he’s strong at that weight. He’s going to be a different guy."

No wonder Ruiz Jr felt the need to apologise to his family and trainer after the bout.

Judging by his father's comments, he's only got himself to blame for losing his belts.