Over the last few years, North London derbies have been presaged by discussion of whether the balance of power has shifted from Islington to White Hart Lane, but this time it feels as though it might actually – finally – have happened.
If Tottenham Hotspur beat Arsenal on Sunday, they will move seven points clear of them with 10 Premier League games of the season remaining and – surely – be on their way to finishing the campaign above them for the first time since 1994/95.
This is Spurs, of course, so the potential to self-destruct remains ever-present. There are plenty of cautionary tales to inspire anxiety, none more so than the final day of the season in 2005/06, when Spurs led Arsenal by a point going into the final game of the season.
Undone by a bout of food-poisoning – the notorious "Lasagne-gate", where over half the Spurs first team reported ill on the morning of the match – they lost at West Ham United while Arsenal, in their final game at Highbury, beat Wigan Athletic to clinch the final Uefa Champions League qualification spot away from their great rivals.
This season, as Chelsea continue to struggle, both could yet finish in the top four – but there is no doubt that, at Spurs at least, breaking Arsenal's dominance is the bigger priority.
Lasagne-gate was the first of five instances in the past seven years when Spurs have finished one place below Arsenal. They keep sneaking up on their rivals' shoulders but never seem to have enough gas in the tank to surge by. The last two meetings must also make Spurs fans uneasy.
Last February, Arsene Wenger was under intense pressure after Arsenal had lost to AC Milan in the Champions league and to Sunderland in the FA Cup, while Spurs had just beaten Newcastle United 5-0, part of a run of 23 games in which they had lost only once.
Spurs went 2-0 up but ended up losing 5-2. The "Mind the Gap" T-shirts that an enterprising Spurs fan had printed to mock their rivals were rapidly taken off the market.
Last November, Spurs again went into the derby in better form. Again they went 2-0 up. And again they lost 5-2. That prompted Andre Villas-Boas's infamous press conference in which he insisted his side had "controlled" the game. It was a comment that drew derision and yet it was not quite as ridiculous as it was made to sound. There had been periods in the second half when Tottenham, despite being down to ten men after the dismissal of Emmanuel Adebayor, did enjoy periods of sustained possession and did pose a threat.
For a manager of Villas-Boas's mindset, those were extremely positive signs. He wants his side to be compact and to control the ball, and in that second half they showed they could do that. He was proved right: since then, Spurs have lost just one of 15 games in the league.
More than that, they have momentum and, in Gareth Bale, a player who is capable of producing spectacular moments. His last-minute winner against West Ham last Monday, smashed in from 30 yards with barely a glance goalwards, was not merely brilliant but seemed to signal Tottenham's change of personality: as the midfielder Scott Parker reflected, in previous years, it was the sort of momentum-shifting goal Tottenham's rivals were prone to scoring.
"We don't plan for anybody," Wenger said when asked about Bale, trying to list great individuals Spurs have had in the past and coming up with only David Ginola and Darren Anderton. "There is nobody special that you least like to face."
Yet with Bacary Sagna injured, Carl Jenkinson is handed the task of trying to stop Bale.
Villas-Boas, named Manager of the Month last week, was reluctant to follow Bale in hailing Spurs as the pre-eminent side in North London.
"Only through time will we be able to say that," he said. "It won't be because of one season that [the balance of power] has shifted."
One season does not change the landscape. But after going so close so often, and with the chance to put daylight between them and Arsenal, this afternoon's game has the feel of a potentially hugely significant encounter.
It is time, perhaps, to dust down those Mind the Gap T-shirts.
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