On the occasion of his US debut and despite being the significant favourite against an opponent who had been given little more than a month’s notice and had lost his only previous world title fight, Joshua suffered four knockdowns in what became a one-sided upset.
He was eventually rescued in the seventh round by referee Mike Griffin when, after returning to his feet for the fourth time — the two knockdowns in the seventh followed two similarly hurtful ones in the third, which came after Ruiz Jr’s only knockdown — he was no longer able to defend himself.
The 29-year-old had established himself as the world’s leading heavyweight by so memorably retiring Wladimir Klitschko in 2017, but so unexpected a defeat has damaged his reputation, contributing to his desire for a rematch in the winter.
“Look out for the end of the year, and what’s next,” said Joshua, like Ruiz Jr aged 29.
“It’s an upset, it’s unexpected. I was the favourite. One shot hit me on the top of the dome and rattled me a bit. I tried to stay in there a few more rounds but the better man won.
“I don’t underestimate anyone. He’s a decent puncher, a decent fighter. He was the better man.
“I’ll tidy up, brush off the cobwebs and go again. But it’s a minor setback.
“Trust me, where I was at in life, I’ve dealt with more s*** than this, with some real big losses, and bounced back.
“If I was to look at my setbacks back then then I would have been f*****. I didn’t. I kept my head strong, fought like a champion, and bounced back.
“I didn’t even ask about a rematch clause because I was so confident I was going to win. If it’s there, we’ll go again and I’ll get the titles back. I’m going to beat him up.
“I’m not dwelling on it. You just correct it, you adjust, you sit down, you focus and you go again.”
Joshua also revealed that he had also already spoken to his mother Yeta Odusanya, and his father Robert, who had given him some advice.
“My dad’s upset, which is a natural reaction; my mum’s cool, she doesn’t come to the boxing and separates it,” he said.
“Everyone’s in good spirits; losing isn’t a good night but it’s something we can learn from.
“My dad said ‘Tighten up and get smart; when things are going good nothing’s going wrong, then something bad happens, you realise’.”
Joshua’s promoter Eddie Hearn, who had previously secured the now-suspended Jarrell Miller as his opponent, also revealed that the UK is the likeliest venue for the rematch that can be expected to follow.
“We didn’t know what was coming next, in November, December, now we do,” he said. “But there’s a lot of pressure on that fight; the rematch is huge.
“For me, it should be the UK, but we’ll sit down as a team and look at everything.
“I know it didn’t go our way but we said we wanted to create a night that people would remember for a long time; unfortunately they’ll remember it for a shock defeat and an incredible night of boxing.
“But that’s okay; revenge will be sweet and I believe he’ll get it.”