The Mexican-American heavyweight stunned the boxing world by knocking AJ out on June 1 at MSG with Joyce more shocked than most.
Britain’s ‘Juggernaut’ has spent plenty of time working with AJ as part of the Team GB amateur setup in the past and also witnessed Ruiz sparring at his old training camp in America.
From his experiences with both men, he quickly made his mind up about who would win.
Joyce explained on the talkSPORT Sports Breakfast: “I thought he [Joshua] would dispatch him quite easily because Ruiz was up in Big Bear [California] where I was training with Abel Sanchez.
“He was sparring with Charles Martin who Joshua flattened to get his first world title.
“I didn’t really think too much of Ruiz and he didn’t want to spar me!
“I don’t think his fitness was there because he could only do roughly two rounds with Charles Martin! And he didn’t want to spar me.
“I didn’t really think he could do it.”
As it happened, Ruiz got up from a third round knockdown to floor Joshua four times and cause the seventh-round stoppage.
There have since been multiple conspiracy theories suggesting ‘explanations’ for the result, and Joyce admits that he doesn’t quite know what to make of it all.
“I saw his fast hand speed on the pads and stuff, but I was very shocked that night.
“I thought maybe Joshua was out of the ring for too long and he was a bit rusty.
“Or the New York crowd got to him, I don’t know what happened.”