An era ended in April. Tottenham beat Arsenal to ensure that, for the first time since 1995, they were mathematically certain to finish ahead of their neighbours.
If it is too soon to declare that Spurs will emulate the Gunners by embarking on two decades of dominance in north London, the balance of power has shifted.
Arsenal fans, borrowing from a slogan used by the London Underground, used to sing "Mind the gap" to their Tottenham counterparts. Now the gap is four points; it will be seven if Tottenham win today. Already, Arsene Wenger has had to deny that his side are underdogs.
And yet, if beating Real Madrid ranks as the biggest statement of Spurs' season, victory now would be a seismic step forward. Despite the better recent derby record, they have only won once in their last 27 visits to Arsenal. Interestingly, they have led twice at the Emirates under Mauricio Pochettino.
Arsenal's doggedness has been apparent, but until recently, they used to eviscerate Tottenham, brush them aside with conspicuous ease or entertain in high-scoring thrillers. That all changed when Pochettino, who is unbeaten in league derbies, took over.
Instead, Arsenal's sole league win in 13 months against top-six opposition came at the expense of a weakened Manchester United team.
ENGLISH PREMIER LEAGUE
Arsenal v Tottenham: Ch102 & Ch227, 8.30pm
Leicester v Man City: Ch102 & Ch227, 11pm
Liverpool v Southampton: Ch103 & Ch228, 11pm
West Brom v Chelsea: Ch104 & Ch229, 11pm
Crystal Palace v Everton: Ch105 & Ch230, 11pm
Burnley v Swansea: Ch106 & Ch231, 11pm
Bournemouth v Huddersfield: Ch107 & Ch232, 11pm,
Man United v Newcastle: Ch102 & Ch227, tomorrow, 1.30am.
Watford v West Ham: Ch102 & Ch227 , 11.55pm
Brighton v Stoke: Ch102 & Ch227, Tuesday, 4am
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Wenger complained about officiating in their 3-1 defeat at Manchester City 13 days ago, but the better team won. So Arsenal could do with displaying their quality on such a stage. But that prompts the question of how many of their quality players Wenger will unleash.
Alexandre Lacazette struck twice against Germany on Tuesday and was a scorer at City, but only after being benched. Wenger claims he trusts his record buy but is yet to start Lacazette, Mesut Ozil and Alexis Sanchez together against elite opposition. He has tended to shoehorn a workhorse into the front three and he must change that.
Factor in Aaron Ramsey and Arsenal could field an ultra-attacking quartet while Tottenham will be without their best defender, Toby Alderweireld. It could encourage Pochettino, who has amended his high-pressing game of late, to again defend deeper and counter-attack.
Sadly for him, Wenger is unlikely to field midfielder Francis Coquelin in the middle of a back three again.
Arsenal will be defending a 100 per cent home league record with actual defenders. Spurs will be attacking it with a changing cast list. Harry Kane, Dele Alli, Harry Winks and Hugo Lloris are back in training after minor injuries, but Pochettino's plans depend on who is fit.
Their verve helps Spurs seem younger and sharper, tactically better and on an upward curve while Arsenal are stagnant.
They got a 90-minute illustration of the changing dynamic in the capital in April. An encore today would be almost as significant.
ARSENAL V TOTTENHAM
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