Twenty years ago, Mike Tyson was the boxing equivalent of the UCLA basketball team of the early 1970s or the Oklahoma football team of the mid-1950s: essentially unbeatable.

As a new decade began, Tyson was far and away the most dominant heavyweight in the world. He entered 1990 with a 37-0 record and 33 knockouts, as well as an aura of invincibility. He was widely feared and made opponents melt just by sneering at them.

His punching power was such that he’d knock down men twice with the same punch; they’d go down from the blow, attempt to rise and fall again. At the time, he was even more feared as a puncher than the previous generation’s heaviest hitter, former heavyweight champion George Foreman.

Tyson walked to the ring on Feb. 11, 1990, in Tokyo (Feb. 10 in the U.S.) to face Buster Douglas as such an overwhelming favorite that only one Las Vegas casino dared put odds on it.

The Mirage, open only a few months, made Tyson a whopping 42-1 favorite to retain his title. That meant that in order to make a $100 profit, a bettor had to lay $4,200.

Douglas entered the fight largely considered a disappointment who would give in when the going got rough. He was the type that Tyson was generally able to intimidate in the prefight buildup and make short work of in the ring.

Douglas, though, was a talented athlete and gifted boxer who had never been particularly motivated. But his mother died three weeks before the bout and he suddenly had more motivation than he could ever need.

He wanted to win the belt to honor his mother. It was straight out of a Hollywood script, except it was 100 percent real.

And that’s why Douglas’ 10th-round knockout over Tyson is boxing’s greatest upset of the last 50 years.

Here is a look at the top 10 upsets in that time:

1. Buster Douglas KO10 Mike Tyson, Tokyo, Feb. 11, 1990: Douglas was 5½ inches taller with a 12-inch longer reach. He used it to pound Tyson with a surprisingly hard and accurate jab, and frequently followed it with a popping right. He used his athleticism to move side to side and neutralize Tyson’s tremendous punching power. Douglas was knocked down in the eighth round, but pounded his fist on the canvas in frustration at his mistake. He arose, boxed well and two rounds later, stopped Tyson in perhaps the biggest upset in sports history.

2. Kirkland Laing W10 Roberto Duran, Detroit, Sept. 4, 1982: Duran entered the bout with a 74-3 record and an impressive victory over the great Sugar Ray Leonard. His only losses were to two Hall of Famers, Leonard and Wilfred Benitez, and to the very tough Esteban DeJesus. Laing was a Jamaican living in England known as “The Gifted One.” Still, Laing entered the bout with just a 23-3-1 record and no wins of note. Duran was coming off losses to Leonard in the infamous “No mas” fight and to the great Benitez: He was simply looking to get back on track and was expected to destroy Laing. He set a fast pace in the bout, which Laing matched. Laing showed a surprising ability to absorb Duran’s best body shots. Duran began to fade in the later rounds and Laing did not. He pulled out a split-decision victory over one of the top 10 fighters in boxing history. Laing would be knocked out in his next bout by Fred “The Pumper” Hutchings. But he put his name into the history books with the notable win over Duran.

3. Leon Spinks W15 Muhammad Ali, Las Vegas, Feb. 15, 1978: It seemed almost preposterous to put Spinks to the same ring as Ali, even though Ali was closer to the end of his magnificent career than the beginning. Spinks was just 6-0-1 as a professional and his most significant performance had been a 10-round draw with veteran Scott LeDoux. He gave up years of experience, as well as 27 pounds, to Ali. But Ali wasn’t particularly interested in working hard that night and hadn’t taken his training too seriously, either. Spinks, on the other hand, could probably have fought hard for 25 rounds, not just 15. His relentlessness and unyielding motor led him to the shocking victory. Ali simply wasn’t in good enough condition to keep Spinks from mauling him, and Spinks won a well-earned split decision.

4. Cassius Clay TKO7 Sonny Liston, Miami Beach, Fla., Feb. 25, 1964: The young Clay had been the light heavyweight gold medalist at the 1960 Olympics in Rome and was clearly a talented prospect. But in 1964, Liston was what George Foreman would be in the 1970s or Mike Tyson was to become in the 1980s: the most feared knockout artist on the planet. He entered the fight 35-1 and was coming off back-to-back first-round knockouts of Floyd Patterson. Clay behaved erratically in the prefight buildup and most assumed he was afraid. Clay had just turned 22, but he was wily enough to concoct a plan to rile Liston. Liston was enraged and tore at him. Clay, who would change his name to Muhammad Ali after the fight, used his speed, quickness and lateral movement to outclass Liston. He kept a jab in Liston’s face, countered him beautifully and frustrated the bully by never standing in front of him flat-footed. Liston quit on his stool after the seventh round, citing an injured shoulder, but it was clear that the young Clay had beaten the fight out of him.

5. Ross Puritty TKO11 Wladimir Klitschko, Kiev, Ukraine, Dec. 5, 1998: Klitschko was the 1996 super heavyweight gold medalist at the Atlanta Olympics and had built a 24-0 record as a professional going into the fight with Puritty. Klitschko was big, powerful and athletic and was widely viewed as a future superstar. Puritty was a solid journeyman who had been in with the likes of Hasim Rahman, Chris Byrd, Tommy Morrison and Michael Grant, but Klitschko was an overwhelming favorite. The fight, though, highlighted one of the shortcomings of Klitschko’s career. He was comfortably ahead when he badly ran out of gas in the 10th round. Puritty knocked him down in that round and finished off a visibly weakened Klitschko in the 11th. Klitschko would go on to win a world title less than two years later, while Puritty would go just 6-7-2 after that fight. Klitschko is now among the most dominant champions in boxing, making the upset even more remarkable in retrospect.

6. Muhammad Ali KO8 George Foreman, Kinshasa, Zaire, Oct. 30, 1974: Most of the great upsets involve a little known or lightly respected winner. Such is not the case in this fight. Had Ali retired without fighting Foreman, he still would have been a first-ballot Hall of Famer. This is one of boxing’s great upsets because of the perception of each man at the time of the bout. Foreman was 40-0 with 37 knockouts and was easily destroying men who had given Ali fits. Ken Norton had split a pair of fights with Ali, though many observers thought he deserved the decision in both, heading into a fight with Foreman. Foreman knocked him out in the second round. Joe Frazier had beaten Ali in their epic 1971 fight and had lost a tough decision to him in a tough 1974 bout. Many openly feared for Ali’s safety against Foreman. But Ali devised the “Rope-a-Dope” strategy, noticing in earlier fights that Foreman tired easily. Ali laid on the ropes in the early rounds, covered his face with his arms and hands and allowed Foreman to beat on him. When Foreman tired, as Ali expected, Ali opened up and knocked out Foreman to become only the second man to regain the heavyweight title.

7. Hasim Rahman KO5 Lennox Lewis, Carnival City, South Africa, April 22, 2001: Lewis was clearly the best heavyweight in the world going into the fight and was on a roll. He was coming off impressive victories over Evander Holyfield, Michael Grant, Francois Botha and David Tua and seemed to be headed for a showdown either with one of the Klitschko brothers or with Tyson. Rahman was a solid professional, but never was considered of championship timber. His most notable win had been a knockout of Corrie Sanders, but he’d lost winnable fights to the likes of Tua and Oleg Maskaev. The key, though, was that Lewis had been making a movie prior to the fight and arrived in South Africa late. Rahman arrived early and adjusted to the time change. He was in shape and in the fifth round caught Lewis with a combination and knocked him out. Lewis would reclaim the title in a rematch seven months later and Rahman would never win another significant fight.

8. Willy Wise W10 Julio Cesar Chavez, Las Vegas, Oct. 2, 1999: Chavez was clearly nearing the end of a fabulous career in which he established himself as one of the greatest boxers ever. He was 102-3-2 at the time, which made Wise’s record of 23-6-4 seem inconsequential. Wise had no significant wins and entered the fight on a three-bout losing skein. But he was known as “Slick Willy” and was able to outbox an out-of-shape Chavez and win a clear unanimous decision victory.

9. George Foreman KO10 Michael Moorer, Las Vegas, Nov. 5, 1994: Foreman was in his second career at the time he met the then-unbeaten Moorer. He was the cheeseburger-munching, grill-pitching fat guy attempting to become the oldest heavyweight champion in history. He was 45 and had failed in two previous post-40 title challenges, against Evander Holyfield and Tommy Morrison. Moorer was 35-0 and controlled most of the fight. He outboxed and outworked Foreman and was ahead comfortably on the scorecards after nine rounds. As Foreman walked out of his corner for the 10th, his trainer, Angelo Dundee, said to him, “You have to put this guy down. You’re behind, baby!” Foreman’s left eye was closing from being hit repeatedly by Moorer’s jab and, fighting for the first time in 17 months, he was beginning to tire. But he ripped Moorer with a straight right that put the champion down and out. HBO announcer Jim Lampley famously said, “It happened! It happened!” after referee Joe Cortez counted Moorer out.

10. Evander Holyfield TKO11 Mike Tyson, Las Vegas, Nov. 11, 1996: Just over two years after Foreman’s upset of Moorer, Holyfield pulled off another major stunner in the same ring at the MGM Grand Garden Arena. Holyfield had been a great champion and was headed to the Hall of Fame, but he seemed finished when he got the Tyson fight. He was thought to be beset by health problems and the Nevada Athletic Commission sent him to the Mayo Clinic for a battery of tests before approving him to fight. Bookmakers, though, didn’t mind that he passed, because they tabbed him a 24-1 underdog. Holyfield was never intimidated and wound up bullying the bully. Tyson had gone to prison after his loss to Douglas, but upon his release, had reestablished himself as the top man in the division. He ripped through contenders at a frightening pace and few, other than Ron Borges of the Boston Globe and Bruce Keidan of the Pittsburgh Post-Gazette, gave him a shot. But he wasn’t intimidated by Tyson, fought back hard and eventually forced referee Mitch Halpern to stop the bout in the 11th round.

10 other upsets of note: Frankie Randall W12 Julio Cesar Chavez, Las Vegas, Jan. 24, 1994; Vince Phillips TKO10 Kostya Tszyu, Atlantic City, N.J., May 31, 1997; Oliver McCall TKO2 Lennox Lewis, London, Sept. 24, 1994; Iran Barkley KO3 Thomas Hearns, Las Vegas, June 6, 1988; Nigel Benn KO10 Gerald McClellan, London, Feb. 25, 1995; Corrie Sanders TKO2 Wladimir Klitschko, Hannover, Germany, March 8, 2003; Zahir Raheem W12 Erik Morales, Los Angeles, Sept. 10, 2005; Glen Johnson KO9 Roy Jones Jr., Sept. 25, 2004, Memphis, Tenn.; Roger Stafford W10 Pipino Cuevas, Las Vegas, Nov. 7, 1981; Leotis Martin KO9 Sonny Liston, Las Vegas, Dec. 6, 1969.