Perhaps Robin van Persie's 92nd-minute free-kick trumps Rio Ferdinand's coin-bloodied eyebrow as the iconic moment from Manchester United's 3-2 victory against Manchester City at the Etihad in December 12. Or the sight of Joe Hart restraining a Blue from leaving a shiner on the defender's other eye for daring to celebrate a last-minute winner that sent a table-topping United side six points clear of the Premier League holders after 16 games.
It is one of the more dramatic derbies in recent memory and served as the defining victory in United's last veritable title bid. Six-and-a-half years of anguish have followed.
David de Gea, the only world-class member of United's squad in the interim, returned in goal that afternoon after a run of four games on the bench as the goalkeeper, whose training under Sir Alex Ferguson was geared to gaining a stone in weight, continued to adapt to the demands of the Premier League.
It was the end of a second spell out of the side in his second season at the club and De Gea, more aggressive, more assured, more dependable, never looked back. The Spain international, who has never been dropped on account of form since, won United's player of the year award in four of the five seasons that followed in a show of consistency to which no United player has even been close.
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His infinite powers have escaped him with concerning regularity over the past 12 months, however. De Gea is acutely aware of that and his confidence has dipped amid the string of high-profile errors in four of United's last five games. The 28-year-old is determined to use the opening weeks of the summer break to clear his head before identifying the cause and finding a solution for for a loss of form that has tarnished his reputation as the world's best goalkeeper since last summer's World Cup.
It is a recovery process that will play out in tandem with, and be influenced by, the decision as to whether a clean slate is required to return to the peak of his powers. Paris Saint-Germain, whose current goalkeeper, Gianluigi Buffon, turned 41 this year, have made an approach for De Gea which is being given serious consideration after United's failure to qualify for the Champions League was confirmed by their draw at Huddersfield last Sunday.
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De Gea's ambition is to add a Champions League winner's medal to his collection, as reported in March, and the chances of doing so in the near future at Old Trafford are slim to none ahead of a third Europa League campaign in nine seasons. It seems logical for De Gea to want success at the highest level but the important caveat remains that he is conscious of the regard in which he is held by United's following who have stood by him at his lowest ebb.
It is a support that has not been forthcoming while on international duty with Spain and De Gea is fond of life at United which, a friend notes, is 'everything De Gea knows' after signing on as a 19-year-old in 2011. His partner, Edurne, has relocated to Manchester and Emilio Alvarez, the United goalkeeping coach with whom De Gea worked at Atléico Madrid, is a close confidant. Any decision to leave the club after eight years will not be taken lightly - or rushed.
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Sergio Romero, the Argentina goalkeeper, is an able deputy whose performances when called upon have left the relevant decision makers at Old Trafford with few doubts about his ability. Dean Henderson, the 22-year-old, won the Championship's golden glove with 21 clean sheets during Sheffield United's promotion campaign and his concerns surrounding a lack of first-team opportunities at United have reduced in recent weeks. His profile matches those of the outfield targets Declan Rice, Callum Hudson-Odoi and Jadon Sancho.
Movement on De Gea's future is expected after Sunday's Premier League finale against Cardiff. His lap of appreciation at Old Trafford will be telling.
