Below are the 15 biggest upsets in boxing history, including Ruiz’s stunner, listed in reverse chronological order.Join DAZN and watch Gennadiy Golovkin vs. Steve Rolls on June 8The 15 biggest upsets in boxing historyAndy Ruiz Jr. TKOs Anthony JoshuaJune 1, 2019The bout was supposed to bring fight fans one step closer to seeing Joshua battle Deontay Wilder for the undisputed heavyweight crown. Instead, it crowned a new unified world heavyweight champ.Ruiz knocked Joshua down four times en route to a seventh-round TKO that not only ruined the British boxer’s U.S. debut, but flipped the state of the heavyweight division upside down.Andy F—ING RUIZ JR. #JoshuaRuiz pic.twitter.com/bjjNhWlbTD— DAZN USA (@DAZN_USA) June 2, 2019Antonio Tarver def. Roy Jones Jr.May 15, 2004At this time, Jones was regarded as the pound-for-pound best fighter on the planet with a record of 46-1 and his only loss coming on a questionable disqualification to Montell Griffin in March 1997. (Jones won the rematch almost five months later.) Jones was coming off becoming the first middleweight champion to win a heavyweight title when he defeated John Ruiz to win the WBA title in March 2003.In his next time out in November 2003, Jones went back down to light heavyweight and won the WBC belt from Tarver by majority decision. Tarver felt he got robbed and demanded they fight again. The rematch took place six months later.Tarver left no doubt who won this time around, as he connected on a flush counter left hook to end Jones’ amazing run.Lamon Brewster KOs Wladimir KlitschkoApril 10, 2004Klitschko was regaining his strength, getting two wins under his belt following his shocking loss to Corrie Sanders more than a year prior when he stepped into the ring with Brewster. Klitschko was the favorite entering the fight and looked to be on his way to victory, dropping the American in the fourth round.But Brewster began sitting on his punches in the fifth and wobbled Klitschko up against the ropes, prompting the ref to register a standing-eight count to the Ukrainian. Klitschko’s legs were completely gone, and the ref stopped the fight seconds later, allowing Brewster to claim the then-vacant WBA heavyweight title.Klitschko wouldn’t taste defeat for another 11 years, further proving how big Brewster’s upset was.Corrie Sanders def. Wladimir KlitschkoMarch 8, 2003Klitschko was 40-1 and looking to make his sixth defense of his WBO heavyweight title. Meanwhile, Sanders was a solid 39-2 but had only fought twice in the past two years entering the fight. That, and the fashion that Sanders disposed of Klitschko, made the upset all the more mind-boggling.Sanders knocked Klitschko down four times en route to the jaw-dropping, second-round TKO.Hasim Rahman KOs Lennox LewisApril 22, 2001Rahman chased Lewis across the ring with four jabs before he unleashed a thunderous overhand right that dropped the unified heavyweight champion of the world flat on his back with a thud, unable to beat the count.Just like that, a new champ was crowned in South Africa via a stirring fifth-round KO.Evander Holyfield def. Mike TysonNov. 9, 1996Holyfield and Tyson were supposed to face each other in 1991, but Tyson had to pull out due to injury and then went to prison in 1992. Five years later, they met for Tyson’s WBA and WBC heavyweight titles.Holyfield was a 25-1 underdog after losing by knockout for the first time in his career in the trilogy fight against Riddick Bowe and a lackluster win over Bobby Czyz. But Holyfield defied the odds and bullied the “bully” throughout to stop Tyson in the 11th round and become a three-time heavyweight champion.George Foreman def. Michael MoorerNov. 5, 1994Moorer was coming off winning the IBF and WBA heavyweight titles from Holyfield. He wanted a big name for his first title defense. Look no further than the 45-year-old Foreman.For nine rounds, Moorer was running laps around Foreman. But in the heavyweight division, all a fighter needs to do is land one punch, and Foreman did just that in the 10th round when he landed a short right hand straight to the jaw to drop Moorer.Referee Joe Cortez waved the fight off, and Foreman became the oldest heavyweight champion in boxing history.Frankie Randall def. Julio Cesar Chavez by split decisionJan. 29, 1994Chavez had come into the tilt on a 90-fight unbeaten streak (89-0-1). Randall was no slouch, as he was 49-2-1. But Chavez was expected to run through Randall and continue his record streak.Randall had other plans. He dropped Chavez in the 11th round, and Chavez got two points deducted for low blows that allowed Randall to pull off the upset.Michael Bentt KOs Tommy MorrisonOct. 29, 1993Morrison was the reigning WBO heavyweight champion, a title he claimed after beating Foreman in June of 1993, and was riding a 10-fight winning streak when he faced Bentt, a heavyweight who was relatively unknown at the time. But the underdog Bentt shocked Morrison and dropped him three times in the first round before a nationally televised audience on HBO for the improbable first-round TKO.The stunning upset derailed Morrison’s immediate plans for a fight with Lennox Lewis, although the scrap would happen about two years later.Buster Douglas KOs Mike TysonFeb. 11, 1990Douglas was a staggering 42-to-1 underdog against Tyson back in February 1990 at the Tokyo Dome in Japan for their heavyweight title fight. But having lost his mother 23 days before the fight lit a raging fire inside Douglas, who took it to Tyson en route to pulling off a shocking 10th-round KO of “The Baddest Man on The Planet” and becoming the new undisputed heavyweight champion of the world.What started as a foregone conclusion that Douglas would lose wound up being the biggest upset in the history of boxing and, perhaps, all of sports.Muhammad Ali def. George ForemanOct. 30, 1974Foreman came into “The Rumble in the Jungle” 37-0 and had just ran through Joe Frazier and Ken Norton in two rounds. Ali’s own battles with Frazier and Norton had taken their toll, and Ali at this point was starting to lose his patented speed and reflexes.Instead of trying to outgun Foreman, Ali used the “rope-a-dope” strategy that ended up tiring his opponent. Ali took advantage of a weakened Foreman to knock him out in the eighth round and put an end to the vaunted winning streak.Cassius Clay stops Sonny ListonFeb. 25, 1964Liston had tasted defeat only once before in his career and had built himself up to being one of the most feared heavyweight champions in boxing history when he faced a 7-to-1 underdog in a brash, 22-year-old Clay.While Liston went for the knockout early, Clay avoided the early damage and blinded Liston with speed, pummeling the champ to the point that he couldn’t continue following the sixth round. He then dismissed any notion that the upset was a fluke by scoring a first-round KO of Liston in their rematch in May of 1965.MORE: Join DAZN and watch more than 100 fight nights a yearRandolph Turpin def. Sugar Ray RobinsonJuly 10, 1951Robinson was a ridiculous 128-1-2 when Turpin handed him his second pro loss and took his middleweight title in a grand upset.Robinson exacting revenge with a 10th-round TKO a couple months later didn’t negate the magnitude of what Turpin was able to do in their first meeting.Max Schmeling KOs Joe LouisJune 19, 1936Louis defeating Schmeling was considered to be all but a formality back in 1936. So imagine the shock when the underdog controlled the fight at Yankee Stadium before emphatically ending it with a 12th-round KO.James Braddock def. Max BaerJune 13, 1935The 2005 biopic “Cinderella Man” told the life story of Braddock, who had a staggering 25 losses on his record when he went up against Baer as a 10-to-1 underdog in June of 1935 in New York. Not only did Braddock prove critics wrong, but he smothered Baer en route to a unanimous decision after 15 rounds, cementing one of the biggest upsets in boxing history.-(Sporting News boxing writer Steven Muehlhausen contributed to this list.) Andy Ruiz Jr.’s shocking, seventh-round TKO of Anthony Joshua to become the new unified world heavyweight champion on Saturday night instantly went down as one of boxing’s biggest upsets.It also made Sporting News recall some of the other massive upsets in boxing history.