Carl Frampton
Former world champion on BBC Radio 5 live

Anthony Joshua expects it to be over when he knocks people over, but this kid got up and put him down.

There are big questions about AJ's engine now and Andy Ruiz Jr will target the body again in the rematch.

David Haye
Former world heavyweight champion on BBC Radio 5 live

Andy Ruiz Jr is a boxer and when he got hurt his instinct was to keep fighting. Anthony Joshua is designed to do any sport, he could be a sprinter because he is so athletic.

Anthony Joshua's invincibility has gone now and he is now just a mere mortal. Now, fighters know they have just got to stick in there against him and keep throwing body shots.

Lewis: All the new fans to boxing through Anthony Joshua have learnt a good lesson - not even your heroes are unbeatable

Jonny: AJ doesn’t really seem to have a chin! Can’t deal with the combination of speed and power

Rob: You lose your world titles to an out of shape guy who only had a few weeks to prepare, then you smile and laugh about it with him afterwards? Nah. He's lost his passion.

Andy Ruiz, the kid who was bullied for being overweight, the man who was mocked for his conditioning and written off by the boxing world, has stunned us all.

What a story.

Remember, he only took this fight at six weeks' notice after Darrell Miller returned an "adverse finding" in a drug-testing sample.

Tyson Fury has tweeted the following...

Image source, .

Carl Frampton
Former world champion on BBC Radio 5 live

This is the biggest shock I have ever seen in my whole days in boxing, and it's live. I liked Eddie Hearn's honesty by saying Anthony Joshua must win the rematch. Where does he stand if he loses that?

Mike Costello
BBC Sport boxing correspondent at Madison Square Garden

Anthony Joshua looked vacant in the ring after the fight.

• Anthony Joshua, after a slow start, knocked down Andy Ruiz in the third round.
• However, less than a minute later, Ruiz knocked down Joshua, who gets up and then gets knocked down again in the same round - the third.
• After a quiet fourth, Joshua looked to enjoy a fifth round, but at the end of the sixth looks like he is out of energy, not engaging for the last 30 seconds.
• Joshua is knocked down twice more in the seventh round (for the third and fourth times overall). He gets up both times, but after the second one does not respond to the referee's instructions and the referee then stops the fight.
• Ruiz takes the IBF, WBA, WBO, IBO world titles
• Promoter Eddie Hearn says a rematch is likely in either November or December.

BBC Radio 5 Live

Speaking to BBC Radio 5 Live, Eddie Hearn said: "I didn't think it could happen but Anthony Joshua got sloppy. I thought Andy Ruiz Jr was done after he went down in the third but AJ got caught.

"I thought he would recover but tonight belongs to Andy Ruiz and it goes down as one of those big upsets in heavyweight history. I know how much it will hurt AJ and it will devastate him but Andy Ruiz Jr is a lovely guy and he is the heavyweight champion of the world.

"AJ must win that rematch in the UK because there is nothing after that. He had a stye in his eye but it didn't effect his vision. It was a new environment and that is a factor but he should be beating Andy Ruiz.

"He is Mexico's first heavyweight world champion but now we have to rebuild. The pressure is on now and he must win to get back to the heights he has been at. He will bounce back and he will give everything he can."

Anthony Joshua, speaking to Sky Sports Box Office, says: "Boxing is a tough sport, but I train hard and I got beaten by a good fighter, it will be interesting to see how far he goes, but this is all part of the journey.

"I'm a fighter by heart, boxer by trade, it has got people talking and there's more life in the heavyweight division. When your legs are all over the gaff, you are trying to stabolise. This is the first fight like that. Against Klitschko (when he also got knocked down) I was just tired.

"Congratulations to the first Mexican heavyweight champion. We bounce back.

This is the risk we take, every fighter deserves respect so congratulations to him. I respect every fighter, this is all part of the legacy, it's how strong I came back. He's a champion for now, I shall return."

Andy Ruiz Jr said: "Without my dad this would not have been possible and I just feel so good. This is what I have been dreaming about and I cannot believe I made my dreams come true. I want to thank my team and my family and the sky is the limit.

"That was my first time getting dropped on the floor but it made me want it even more and I just thank god.

"I have got that Mexican blood in me and that just proved it. I could sense Joshua was hurt but I didn't want to throw everything at it, I just wanted to work the body and stick to the game plan. Right now, I just want to celebrate and I made history for Mexico. It means everything."

Carl Frampton
Former world champion on BBC Radio 5 live

It's nice to be gracious and shake your opponent's hands, this is too nice. He (Joshua) should be heartbroken, absolutely gutted and I'm not seeing that. This is a bizarre situation, there are far too many smiles.

Our pundits on 5 Live are a bit bemused by Joshua's behaviour, saying he is looking far too happy at having his unbeaten record and his world titles taken from him.

David Haye
Former world heavyweight champion on BBC Radio 5 live

He only had six weeks and he won the fight legitimately and he systematically broke down AJ. Will Joshua even want the rematch?

Mike Costello
BBC Sport boxing correspondent at Madison Square Garden

It is a crushing defeat and to be fair to AJ he is smiling and offering congratulations to Ruiz Jr. He has taken the titles in one of the greatest upsets in the history of boxing.

Seven weeks ago, Andy Ruiz did not have a world title fight, he had to hassle Eddie Hearn on social media to get his shot, now he is holding the IBF, WBA, WBO and IBO world titles.

Andy "The Destroyer" Ruiz. He has just destroyed Anthony Joshua's world.

Steve Bunce
BBC Radio 5 Live boxing pundit at Madison Square Garden

He was a broken man in that round. He spits the gumshield out and goes back to the ropes. The referee has no option but to stop the fight.

David Haye
Former world heavyweight champion on BBC Radio 5 live

I'm completely shocked. I have never seen such an upset in the flesh. what surprised me was the fact AJ lent against the ropes and it was like he didn't want to continue fighting.

Maybe there was some confusion but it looked like he didn't want to walk towards the fight.

They are bound to have a rematch clause in the contract so expect these two to fight again in the next 12 months.