How did George Kambosos Jr. beat Teofimo Lopez, and where do they go from here?

NEW YORK - Teofimo Lopez was on top of the world.

With the win over Vasiliy Lomachenko in December 2020, Lopez was instantly and universally recognized as one of the 10 best pound-for-pound boxers in the world. With a big personality on top of his success, Lopez was on the fast track to superstardom.

Then came the first postponement of his seemingly routine title defense against George Kambosos Jr. -- the result of Lopez's positive test for COVID in June. Chaos ensued, with eight date changes and numerous legal threats that resulted in the fight being pushed to November, a different promoter and a different broadcast platform. Lopez, who hails from Brooklyn, was still on home turf at the Hulu Theater at Madison Square Garden, and a 7-to-1 betting favorite.

But when they finally entered the ring Saturday, Kambosos made sure the fight was well worth the wait. He floored Lopez in the first round and survived a 10th-round knockdown to score one of the biggest upsets of 2021 -- turning the stacked lightweight division upside down.

"I put him on his ass," Kambosos, 28, told ESPN. "From that, I totally changed the fight straight away. He was hesitant. ... We boxed very smart, and you know what I showed? My boxing skills. ... I showed what a true champion is, to come back and win the fight and close it in great fashion."

Lopez (16-1, 12 KOs) was already looking past Kambosos to what he hoped was a massive 2022 filled with three fights. He hoped to kick off the year with a bout against undisputed 140-pound champion Josh Taylor, followed by clashes with Devin Haney and Gervonta Davis.

Of course, all of those potential matchups were far from certain. In the aftermath of the shocking loss, Lopez's future is more unclear than ever.

The 24-year-old Lopez claimed he won 10 rounds and was met by a cascade of boos as he offered that he was weight-drained.

"I don't care what anybody says, I won tonight," said Lopez, who entered the ring Saturday night as ESPN's No. 7 pound-for-pound boxer. "At the end of the day, I've been here, I've done it. Look, I'm not sore loser; I take my wins like I take my losses. At the end of the day, I'm a true champion. I came out here, I did what I had to do and I went out there and I did my best. ... This is the takeover: we don't stop, we keep coming."

The way his face was marked up and the cuts over both eyes told a different story, and Lopez will surely be out of the ring for some time. When he returns, Lopez will likely take the tried-and-true comeback route in boxing that involves a soft touch (or two) before he heads into another major fight. That next title shot will surely come at 140 pounds, but when it happens is another matter.

What was meant as an opportunity for Lopez to regain momentum after 13 months out of the ring turned into disaster. He's proven resilient outside the ring, but the biggest test of his career awaits him. How will he respond to his first professional loss and getting knocked off his pedestal as a unified world champion?

Kambosos, on the other hand, finds himself in uncharted territory. No one gave him much of a chance to win, and it was said he won the lottery after capturing a career-high purse that exceeded $1.5 million. At least one more major payday will follow for the Australian in the star-studded lightweight division, and it could be more. This appeared to be far from a fluke for Kambosos (20-0, 10 KOs), who boxed well over 12 rounds against an elite boxer.

The winner of next week's fight between Haney and Joseph Diaz Jr. is the leading possibility. But there are also marquee matchups with Davis and Ryan Garcia that could be on the table.

"There are a lot of potential paths and frankly, there are 130-pounders looking up at him, there are 135-pounders looking sideways at him and 140-pounders looking down on him," Lou DiBella, Kambosos' promoter, told ESPN. "He has a whole continent of Australia where he is now the man. He's now the No. 1 athlete in Australia. He's going to have a lot of alternatives."

Considering what he accomplished in his victory over Lopez, and his status as a broadcast free agent, Kambosos also has a lot of flexibility in terms of who he can fight, where it'll happen and how to enjoy the spoils of claiming Lopez's world titles.

"I think he's going to sit back, take a little time off and enjoy the victory," DiBella said. "Then we're going to figure out the biggest fight we can make."