Though seen as a massive underdog, Andy Ruiz Jr. has created a big shock in the world of boxing; knocking out Nigeria-born British fighter, Anthony Joshua.

Ruiz (33-1, 22 KOs) made sure he spoiled the long-awaited U.S. debut of unified heavyweight champion, Joshua, to score four knockdowns before recording a spectacular upset via seventh-round TKO at Madison Square Garden.

It was not an easy win for Ruiz though as he had to get up off the canvas early in Round 3 in order to do what oddsmakers felt was nearly impossible.

Ruiz indeed showed tremendous tenacity, power and fearlessness in systematically dismantling Joshua (22-1, 21 KOs) to flip the heavyweight division upside down.

Ruiz, 29, a native of southern California, became the first boxer of Mexican descent to win a heavyweight title as he captured Joshua’s IBF, WBA and WBO titles all in one night.

For boxing bluffs, this upset is arguably the biggest within the division since Hasim Rahman stopped Lennox Lewis in 2001 and brought back memories of James “Buster” Douglas’ 1990 win over Mike Tyson.

“I just want to thank God for giving me this victory. Without him this wouldn’t have been possible,” Ruiz said. “This is what I have been dreaming about. This is what I have been working hard for, and I can’t believe I just made my dreams come true.”

With the sold-out crowd, which was largely in favour of Joshua, stunned and silent following the stoppage, Ruiz jumped around the ring in wild celebration.

“Big respect to Andy, big big respect,” Joshua said. “[He’s a] good fighter. Thank you America. Thank you everyone for coming out this evening. Sorry I let my friends down, sorry I let my supporters down.”

The third round should easily go down as the best of 2019 after Joshua landed a beautiful two-punch combination to floor Ruiz.

However the Mexican seemed to have gotten more energy from that setback as he caught Joshua shortly with a left hook and right hand to the top of the head to drop him.

Ruiz followed up with an unanswered, 12-punch flurry in the corner that fell Joshua a second time as the champion was lucky to survive the round.

“That was my first time getting dropped on the floor,” Ruiz said. “But you know what, it just made me stronger and made me want it even more. I just had to knock him down back.

“I didn’t want to throw everything that I got. I wanted to hunt him down even more, work the body, work the head and just listen to the game plan. We just pulled it off, man.”

On his part, still reacting to how things went for him in the ring, Joshua admitted he had no excuse and would take the blame for the disappointing loss.

“There’s no excuses. It’s my own fault. I got caught with a big shot,” Joshua said. “Congratulations to him. I would have preferred it to be Deontay Wilder, do you know what I mean? But it wasn’t. It was Andy Ruiz, and he deserves it, and the fame and fortune he’s about to receive.

“I don’t want anyone to kind of drown in their sorrows. This is boxing. It’s all the same. It just wasn’t my night. It was Andy Ruiz’s night. You know what? It’s good for the TV. It’s good for DAZN. It gets people watching.”

It is expected that Joshua will seek a rematch as soon as possible as that clause was inserted in the bout contract.