It was a triumph of spirit and determination, a glowing example of what a team can achieve when it refuses to quit.
Since the turn of the year, Chelsea's strength has been the extent of their stamina and sustained effort. They drew on it last night to overcome in extra time the football with which Leeds threatened to destroy them, as they had threatened to win for so much of the time at Wembley two weeks ago.
Here in one match were the extremes of exaltation and despair which are suffered each season in football.
For weeks now there has been an air of inevitability about Leeds' failure. The championship was taken from them by Everton and the European Cup, the most prized of their targets, was left to be contested by Celtic in Italy next week. They are left with nothing. And Chelsea will come home in triumph this morning, handsomely rewarded for the football and effort which has brought them forward as a team of outstanding quality.
But in a match whose undertones of violence were not helped by inefficient refereeing, there were long periods when it looked as though Leeds would run away with it. Referee Eric Jennings was a figure of bland indifference as players went over the ball, and as others fell before crushingly illegal challenges. A mark of Chelsea's committed effort is that their fouls almost tripled those conceded by Leeds.
But this was all a part of of their refusal to give in when their goalkeeper, Peter Bonetti, was limping with a heavily bruised knee after he had been beaten by a thundering shot from Mick Jones.
Leeds had to play without their goalkeeper, Gary Sprake, but his young deputy, David Harvey, rarely had to do more than field back-passes in the first half-hour.
It was in the 35th minute that they struck the first vital blow. Allan Clarke bravely careered through three tackles and then set Jones free through the middle. Bonetti, who a few minutes earlier had been bludgeoned to the floor as Jones challenged on a long cross from Paul Madeley, came limping from his line. But Jones shot with devastating force beyond Bonetti's right shoulder.
Leeds were immediately content to consolidate their lead but they suffered a blow themselves when Eddie Gray was crippled by an appalling foul by Chelsea captain, Ron Harris. Remembering Gray's total domination of David Webb at Wembley, Chelsea switched Harris to full-back.
Chelsea refused to give in, and managed to protect Bonetti from crosses by containing Leeds on the touch-line in the second half. And yet as the game drew on through the final phase of normal time, it seemed that Leeds at last would finish with something.
Then, out of nowhere, Chelsea were revitalised by a great goal. Charlie Cooke sprinted forward to take a pass from John Hollins, and then centred perfectly through Leeds' line of defenders to find Peter Osgood sneaking in to score with a perfect header.
Chelsea lived on to take their reward with a goal whose pattern has been seen many times this season. With only a minute left during the first half of extra time, Ian Hutchinson hurled as long a ball as he has thrown from the touch-line. Harvey, under pressure, could not take it and David Webb, whose enthusiasm typified Chelsea's spirit, thundered in to score at the far post.
It was now Chelsea's Cup as Leeds, remembering that they had shots kicked from the line, and recalling their superiority at Wembley, began to reveal obvious signs of frustration and demoralisation. They pushed Billy Bremner and Jack Charlton forward, but recovery was beyond them.