Rumble in the Jungle
Ali v Foreman, Zaire, 1974
Grandstand, BBC Two, 1630
Upsets do not come much bigger than the night Muhammad Ali rumbled George Foreman in the jungle.
But shocks have been a staple of heavyweight boxing since "Gentleman" Jim Corbett trounced bare knuckle legend John L Sullivan in New Orleans in 1892.
BBC Sport takes a look at five fights that reverberated around the globe.
Hasim Rahman v Lennox Lewis, Johannesburg, 22 April 2001
Pre-fight odds: 20-1
"The Rock" only started boxing when he was 20 and was considered a competent fighter whose best days were behind him when his big chance arrived.
Lewis came into the fight overweight and overconfident, having spent only 12 days acclimatising to the high altitude conditions.
On the night, the champion melted in the heat before Rahman vaporised him with a right hand in the fifth.
The 29-year-old lost the rematch to a refocused Lewis later the same year.
James J Braddock v Max Baer, New York, 13 June 1935
Pre-fight odds: 10-1
Braddock was a 29-year-old father of three and just scraping by when his shot at the big time came against playboy world champion Baer.
Braddock had 22 losses on his record going into the fight, while the talented but profligate Baer was so confident he genuinely thought he might kill his opponent.
As it turned out, a dogged Braddock outboxed and outgamed the posturing Baer and was declared the winner by unanimous decision before a euphoric crowd of 35,000.
Braddock, immediately dubbed "Cinderella Man", clung to his crown for two years before the great Joe Louis destroyed him in 1937.
James "Buster" Douglas v Mike Tyson, Tokyo, 11 February 1990
Pre-fight odds: 45-1
Another 29-year-old, Douglas was a laid-back fighter with a reputation for folding while Tyson was simply the "baddest man on the planet".
Tyson was undefeated and considered invincible, but the death of Douglas' mother shortly before he left for Japan infused in the challenger the will to succeed.
On a spell-binding night in Tokyo, Douglas outjabbed a woefully under-prepared Tyson for round after round before knocking him out in the 10th.
Thereafter, "Buster" went back to his lazy ways and eight months after pulling off boxing's biggest ever coup he capitulated in three rounds to Evander Holyfield.
Cassius Clay v Sonny Liston, Miami, 25 February 1964
Pre-fight odds: 7-1
The 22-year-old Clay was considered to be a loud-mouthed charlatan who would be brutally exposed by the menacing Liston.
The brooding Liston, who crushed Floyd Patterson in one round to win the championship and repeated the trick in his first defence, appeared indestructible.
Clay dubbed Liston the "Big Ugly Bear" in the run-up to the fight and worked himself into such a fit of hysteria, some thought he might be mad.
When fight night came, Clay "shook up the world", bamboozling the ageing champion with his speed and mobility and forcing Liston to quit at the end of round six.
Gene Tunney v Jack Dempsey, Philadelphia, 23 August 1926
Pre-fight odds: 6-1
Tunney was a clean-living ex-Marine with an interest in books while Dempsey was a brawling draft-dodger who led a hellraising life.
It was a classic match-up and 120,000 packed into Philadelphia's Sesquicentennial Stadium to see the "Manassa Mauler" defend his title for the first time in three years.
To the delight of many, the unfancied "Fighting Marine" gave the champion a lesson in scientific boxing on his way to a unanimous 10-round decision.
Tunney won the rematch a year later (famous for the "Long Count") and retired from the ring as champion while Dempsey also had the strength of character to walk away.