"Don't f**k with Australia" - Jake Paul, Manny Pacquiao, and more react to George Kambosos Jr.'s upset win over Teofimo Lopez

George Kambosos Jr. has pulled off one of boxing’s greatest upsets in recent memory after outduelling rising superstar Teofimo Lopez.

The fighting pride of Australia edged Lopez via split decision (115-11, 115-113, 113-114) to become the IBF, WBO, WBA, and The Ring lightweight world champion.

Kambosos came at Lopez from the get-go, dropping the champ with a looping right hand. Lopez returned the favor in the 10th round as he secured a knockdown of his own, but Kambosos quickly recovered and finished strong.

Lopez was not too pleased with the decision. The American did his best Kanye West impersonation, interrupting his opponent's post-fight interview in protest of the result.

Nonetheless, Kambosos shattered all odds despite being continuously overlooked and handed Lopez his first defeat. Here's how some of the biggest names in combat sports reacted to Lopez vs. Kambosos.

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Boxing stars react to Teofimo Lopez vs. George Kambosos Jr.

Boxing legend Manny Pacquiao congratulated his training partner George Kambosos on his monumental win. Over the course of three years, Kambosos was the chief sparring partner for Pacquiao.

During their time together, the pair reportedly sparred for roughly 250 rounds. Kambosos' training sessions with the Filipino icon paid off in a big way as he's now an undisputed champion. Of course, Pacquiao was one of the first people to extend his congratulatory regards.

YouTube star-turned-professional boxer Jake Paul was ecstatic to see Kambosos pull off the upset. Paul took to Twitter to congratulate Kambosos and the entire country of Australia.

Meanwhile, boxing world champ and MMA fighter Claressa Shields said she didn't expect such a flat performance out of Teofimo Lopez. Just the same, Shields celebrated Kambosos' win and welcomed him to the "undisputed club."

Meanwhile, boxing trainer and fight commentator Teddy Atlas believes Lopez and his corner still have a lot to learn after tonight's defeat. He compared the new champ to Italian-Canadian legend Arturo Gatti.

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UFC stars react to Teofimo Lopez vs. George Kambosos Jr.

UFC featherweight champion Alexander Volkanovski was thrilled to see his fellow Aussie bring home the gold. Volkanovski took to Twitter to celebrate his compatriot's victory.

Meanwhile, UFC bantamweight champion Aljamain Sterling admitted he didn't know who Kambosos was prior to the fight. Nevertheless, after the Australian's performance against Lopez, it's safe to assume that Sterling won't ever forget who he is.

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Combat sports journalists react to Teofimo Lopez vs. George Kambosos Jr.

Marc Raimondi of ESPN and Luke Thomas of CBS Sports were both disappointed with Teofimo Lopez's performance. Raimondi believes Lopez "underperformed" while Thomas thinks Lopez looked "unrecognizable".