Back before the world of boxing became clogged up and confused by 'junior' and 'super' titles and weight classes that accommodate men so tiny they could fight on a Petri dish, jumping weight divisions really meant something.This explains why Kell Brook's audacious bid to become only the second man to reign simultaneously as a welterweight and middleweight world champion has attracted so much attention - no stopping off at light-middleweight for Sheffield's Brook, instead he'll challenge Gennady Golovkin for his WBC and IBF middleweight titles in London on Saturday in his first fight at 160lb.
BBC Sport takes a look at eight famous occasions when boxers jumped divisions - or, to use the parlance of the day, 'dared to be great'.
Sugar Ray Leonard v Marvin Hagler, Las Vegas, 6 April 1987As Muhammad Ali's career was spluttering into darkness in the late 1970s, Leonard began to dazzle. In 1979 he dethroned Puerto Rican great and WBC welterweight champion Wilfred Benitez, only to lose his title two fights later to Panama's Roberto Duran, perhaps the greatest lightweight ever.
In 1982 Leonard retired because of a detached retina, and again after a comeback fight in 1984. But missing the limelight, he challenged fearsome middleweight king and fellow American Hagler in 1987.
Many feared for Leonard's health against a man who hadn't lost since 1976, but the naturally smaller man deployed his speed and reflexes to great effect, persuading two of the three judges that the WBC middleweight belt should be his - although many observers believed Hagler was robbed.
Michael Spinks v Larry Holmes, Las Vegas, 21 September 1985Before the cruiserweight division was slowly introduced in the early 1980s, boxers from lower divisions challenging for heavyweight honours were rare.
This didn't deter Spinks, who won the light-heavyweight title in 1981 and defended it 10 times before challenging heavyweight world champion Holmes, who had reigned over boxing's blue riband division for seven years.
Spinks piled on 25lb in two months but still weighed 22lb lighter than Holmes, who was 46lb heavier than anyone Spinks had ever faced. However, Spinks won a unanimous decision to deal Holmes his first defeat and become the first reigning light-heavyweight champion to win the world heavyweight crown.
Henry Armstrong v Barney Ross, New York, 31 May 1938Back when only eight 'pure' weight divisions existed, jumping divisions was a more daunting prospect, given that it usually meant bridging a stone in weight. But in 1938 Armstrong attempted the truly outrageous, challenging for the welterweight world title while still featherweight world champion.
'Homicide Hank' won the 126lb title in 1937, before bypassing the lightweight division and challenging 147lb champion Ross instead. Armstrong was outweighed by 10lb at the Madison Square Garden Bowl but battered Ross for 11 rounds before showing mercy and carrying him for the last four.
Only 10 weeks later Armstrong dropped down to the 135lb lightweight division and outpointed Lou Ambers to complete a remarkable world title 'triple crown'.
Roy Jones v John Ruiz, Las Vegas, 1 March 2003By the early 2000s Jones Jr had grown bored of beating up light-heavyweights who weren't fit to carry his jockstrap and sought greater fame and fortune in the heavyweight division. Conveniently, the heavyweight division had collapsed and the rugged but limited Ruiz was the reigning WBA champion.
Jones won the middleweight world title in 1993 before cleaning up at super-middle and light-heavyweight. But no former middleweight champ had won a heavyweight world title since Cornish-born Kiwi Bob Fitzsimmons in 1897.
It speaks volumes for Jones' prodigious talent (as well as the decrepit state of the heavyweight division) that he was the favourite to beat Ruiz, and so it came to pass. Despite, or because of, being 33lb lighter, Jones comprehensively outboxed Ruiz over 12 rounds and was awarded a wide unanimous decision.
Jose Napoles v Carlos Monzon, Paris, 29 February 1974Perhaps the closest comparison to Brook v Golovkin was when Cuban emigre Napoles stepped up to challenge the great Argentine middleweight Monzon - although Napoles was a far more proven champion at 147lb than Brook, having landed the undisputed world title in 1969 and defended it 11 times.
That said, Napoles had contested 82 pro fights before facing the wild Monzon in his first fight at 160lb - although it should be noted that Monzon had had 93.
Having, like Brook, skipped the light-middleweight division, Napoles found Monzon too big and too strong and failed to answer the bell for the seventh round. Napoles dropped back down and continued to reign at welterweight.
Sugar Ray Robinson v Joey Maxim, New York, 25 June 1952Robinson, probably the greatest boxer who ever lived, had laid waste to the welterweight and middleweight divisions and lost only two of his 135 pro fights before challenging Maxim for the light-heavyweight world title.
To put Robinson's challenge into perspective, he started out as a lightweight. Meanwhile, only two fights before he fought Robinson, Maxim was beaten on points by former world heavyweight champion Ezzard Charles.
Robinson was beaten by the conditions rather than Maxim - with the temperature running at 103 degrees in Yankee Stadium, Robinson, miles ahead on the scorecards, was unable to come out for the 13th round. Still, Robinson lasted longer than referee Ruby Goldstein, who collapsed after the 10th.
Verdict: NEAR MISS
Emile Griffith v Dick Tiger, New York 25 April 1966Virgin Islander Griffith won and lost the world welterweight title several times in the early 1960s, while earning unfair notoriety for killing bitter Cuban rival Benny Paret in 1962, in a bout that was broadcast live on American television.
In 1966 Griffith vacated his welterweight title to challenge Nigeria's middleweight world champion Dick Tiger, who had won the title from American veteran Joey Giardello only six months earlier.
Despite being outweighed by 10lb, Griffith floored Tiger for the first time in the Nigerian's career in round nine before being awarded a narrow decision. The Madison Square Garden crowd booed and 17 out of 22 boxing writers perched ringside thought Tiger had won, but the record books state the opposite.
Amir Khan v Saul Alvarez, Las Vegas, 7 May 2016Brook's compatriot and cross-Pennine rival Khan hoped to become only the third former light-welterweight world champion to win a middleweight world title when he signed to fight WBC title-holder Alvarez earlier this year.
Many observers dubbed the fight a suicide mission on Khan's part - the match was made at a catchweight of 155lb, five pounds below the traditional middleweight limit, but that was still eight pounds heavier than Khan had ever weighed, while a rehydrated Alvarez reportedly weighed 180lb on fight night.
The fight panned out as many had predicted, the Briton using his superior speed to keep his Mexican rival at bay for the first half before walking on to a crackerjack right hand that rendered him unconscious before he hit the canvas. Alvarez promptly vacated his belt rather than face Golovkin.