Anthony Joshua will defend his IBF, WBA and WBO heavyweight titles against Andy Ruiz Jr in New York on Saturday, with few people giving the underdog a chance of victory.
The undefeated Joshua is a strong favourite to beat Ruiz, who was beaten by Joseph Parker in his only previous title fight.
However, there have been no shortage of shock results in boxing over the years, with many of them occurring in the heavyweight division.
Omnisport looks back on some of the sport's biggest surprises.
July 10, 1951: Turpin shocks Sugar Ray
Widely considered one of the finest boxers in history, Sugar Ray Robinson had only been beaten once - by the great Jake LaMotta - in 132 bouts when he defended his world middleweight crown against Randy Turpin at Earls Court Arena.
Turpin was a virtual unknown but produced a sensational display over 15 rounds to dethrone Robinson, who gained swift revenge with a knockout triumph when the pair met again in New York two months later.
February 15, 1978: 'The Greatest' loses Spinks epic
Muhammad Ali was a 1-10 favourite when he first faced Leon Spinks, a man fighting professionally for only the eighth time, in Las Vegas.
After a titanic battle between boxing's biggest star and his underdog opponent, Ali looked to have done just enough when the first scorecard was read out in his favour.
However, the two remaining judges decided Spinks was the winner, despite conceding almost two stones in weight to Ali. Once again, a rematch produced the opposite result.
February 11, 1990: Iron Mike stopped by Buster Douglas
The Tokyo Dome played host to arguably THE biggest boxing upset in history, as Mike Tyson lost his unbeaten record, which had read 37-0 with 33 KOs, to the unheralded Buster Douglas.
Only one casino offered odds on Douglas winning the fight, his price a staggering 42-1. Yet that is what happened, with Tyson left to rue a lack of preparation for a contest he had presumed would prove a breeze. 'Iron Mike' was sent to the canvas in round 10, his aura of invincibility permanently shattered.
April 22, 2001: Rahman rocks Lewis
Hasim Rahman spent a month in South Africa, training at high altitude, ahead of his heavyweight world title fight with Lennox Lewis in Gauteng. In contrast, reigning champion Lewis was there only half as long, instead training in Las Vegas so he could film scenes for a cameo appearance in Ocean's Eleven.
Like Tyson before him, Lewis would pay a heavy price for his apparent over-confidence, as Rahman secured a spectacular knockout victory in the fifth round.
A subsequent rematch saw Rahman beaten in four, with a fiercely focused Lewis earning redemption.
July 2, 2017: Pac Man stunned by hometown hero Horn
Manny Pacquiao's very best years may have been behind him for some time now, but the Filipino great was still a huge favourite when he took on unheralded Australian Jeff Horn in Brisbane two years ago.
However, Horn managed to pull off an incredible victory at Suncorp Stadium, claiming the WBO welterweight belt with a somewhat controversial points victory.
All three judges scored the fight in Horn's favour, prompting surprise in certain quarters, but few could argue that the home boxer had produced anything other than an impressive display in the biggest fight of his life.
Pacquiao has enjoyed an upturn in fortunes since the shock loss, though. The 40-year-old will defend his WBA welterweight title against Keith Thurman at the MGM Grand on July 20.
