The rivalry began in the 60s and cast one as King's Road cavaliers with the other as whippets-and-flat-cap roundheads
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The last time Chelsea played at Elland Road was more than nine years ago, when the symbolism of two clubs meeting each other momentarily while passing on adjacent escalators was striking. The visitors, kindled by a benefactor who would make Croesus feel like Bob Cratchit, were ascending towards establishing themselves among Europe's elite while Leeds United, wrecked by the profligacy of gambling borrowed money on perennial Champions League qualification, plummeted towards a crisis whose depths were not then fathomable.
In the summer of 2003 Chelsea had spent £110m on 13 players, among them Claude Makelele, Adrian Mutu and Damien Duff. By contrast Leeds had been obliged to sell Harry Kewell, Olivier Dacourt and Nigel Martyn and had bolstered a threadbare squad by signing five clients of Willie McKay on loan from the French league together with the 2002 World Cup-winner Roque Júnior and, from Stamford Bridge, the combative midfielder Jody Morris on a free transfer.
By the time of the Chelsea match on 6 December 2003, all had been jettisoned from the starting XI, and the man who signed them, Peter Reid, had also been ousted. Twenty-four points separated Leeds at the bottom of the Premier League and Claudio Ranieri's side at the top but the home side, roused by the caretaker manager, Eddie Gray, who was not as vengeful as some of his colleagues in Don Revie's teams but nonetheless could have been forgiven for harbouring a 33-year-old grudge against Chelsea, put in their most spirited performance of that entire wretched relegation season to emerge with a draw.
Back then it was Leeds who had the superior pedigree – three league titles to Chelsea's one – and although the Blues were on their way to their first Champions League semi-final that season, Leeds had played in three European Cup semis and one final.
Since that game Leeds have spent three seasons in League One and are currently mid-table in the Championship. Chelsea, meanwhile, have usurped them, winning the Premier League title three times, adding four more FA Cups, two more League Cups and 2012's Champions League to their honours board. Where both once met on fairly equal terms as competitive post-war parvenus they now exist in divergent orbits. Yet they share two things – a feisty rivalry based on their history and the pleasure of having Ken Bates as chairman and principal owner.
At the end of Chelsea's last visit Bates still had two months left at Stamford Bridge. He had sold his shares to Roman Abramovich in the summer but had remained as chairman of the football club while Bruce Buck took over his chair at Chelsea Village. However, when his programme notes were omitted on the instructions of the club's chief executive, Peter Kenyon, before the game against Charlton in 2004, Bates took umbrage and walked out a month later.
A flavour of his feelings for the regime that had bought him out emerged when he named one of the number of vehicles associated with the ownership of Leeds since he became the club's chairman in 2005 Romans Heavies.
And now, on the brink of another sale if the exasperatingly prolonged takeover of Leeds by GFH Capital is completed according to schedule on Friday, Bates is finally afforded the opportunity of hosting his old club in the Capital One Cup quarter-final. Abramovich is unlikely to accept his hospitality, he rarely bothers with away games in this competition, but students of Bates's pugnacious matchday column are bracing themselves for a classic.
To some Leeds fans, the ones the owner calls "dissidents" among other epithets taken up as badges of honour, Bates's past with Chelsea defines him. Whenever a decent player is sold – Fabian Delph, Max Gradel, Jonny Howson and Robert Snodgrass, for example – for an undisclosed fee, and the short-termism of the club's strategy is exposed by replacing them with loan signings, the chant "get the Chelsea out of Leeds" gets an airing.
The "Chelsea" part of that refrain is not simply about allegiance. It's about identity. For Leeds, the London club represent something typically metropolitan and louche, all of which stems from a rivalry that began in the 1960s which cast one as King's Road cavaliers, the other as whippets-and-flat-cap roundheads.
Leeds could number Colin Welland and Ronnie Hilton among their fans but they were hardly a match for Chelsea's Raquel Welch and Steve McQueen.
The first evidence of any animosity came during a Second Division victory for Leeds in 1962 over Tommy Docherty's promotion-bound "Diamonds", when United's Eric Smith suffered a broken leg. Five years later the two met in an FA Cup semi-final at Villa Park and in the dying minutes, with Leeds trailing 1-0 to a Tony Hateley header, Peter Lorimer "scored" from a 25-yard free-kick. But since the Chelsea wall had not retreated 10 yards, a rule more honoured in the breach than the observance, the "equaliser" was expunged by the referee, Ken Burns.
Even Kenneth Wolstenholme, decidedly not an Alan Green when it comes to scorn for referees, said: "You'll have to look in the rules book backwards to find a reason." Leeds got their revenge six months later, hammering Chelsea 7-0 in the league, but when they faced each other again in the FA Cup, in the 1970 final, Chelsea's vengeance could be toasted from the trophy.
The match at Wembley was drawn 2-2, Chelsea twice coming back to equalise in a game dominated by Eddie Gray's tormenting of David Webb and settled by a misjudgment from Gary Sprake on a horribly gloopy pitch. The replay at Old Trafford, a fortnight after Leeds had been knocked out of the European Cup by Celtic, has been portrayed as a bloodbath but it took a while to descend into notoriety. It began when Ron Harris, switched to replace Webb at right-back and to deal with Gray, kicked the left-winger across the knee shortly after Leeds had taken the lead through Mick Jones.
From then on Eric Jennings, the referee, tolerated a staggering number of filthy tackles, players squaring up to each other and sly cracks around the head. He gave 35 fouls against Chelsea and 11 against Leeds, but an objective assessment would add 25 to each total. Leeds finally buckled 12 minutes from the end of the 62nd match of their season, Chelsea's finely worked move giving Peter Osgood a free header. In extra time Webb, the weakest link at Wembley, scored the winner, leaving Leeds with nothing after battling so long on three fronts.
The cultural contrasts between those two squads, Chelsea and their wine bars, Leeds and their bingo, have been overplayed, but not their dislike of each other. "It was out-and-out war," said Chelsea's Ian Hutchinson. For most of the next three decades groups of fans took up where the players left off, one sprawling fight in 1982 spread from Piccadilly Circus to Charing Cross station.
In 1984, when Chelsea won 5-0 at Stamford Bridge to seal promotion back to the First Division, some of the Leeds supporters demolished the scoreboard and took fragments of it back to Yorkshire on the train. Mounted police had to disperse those fighting on the pitch.
The old enmity has flickered sporadically since – in 1997 when Leeds under George Graham held on for a 0-0 draw away from home despite having two players sent off – and flared for the next four years in some rough-house interludes between Dennis Wise and Frank Leboeuf on one side Gary Kelly and Alan Smith on the other, but apart from one cherished, derogatory song each, it has lain dormant since 2003.
Jet-lagged and possibly jaded, Chelsea may well adopt the princely hauteur of one accosted by a pauper claiming to have known them before they had made it big. For fans whose perspective extends beyond 1992, however, Wednesday's fixture will always have a particularly spicy resonance.