When this result reached Lombardy, even Milan may have paused for thought. Although it remains highly unlikely Arsenal will overturn the Italian side's 4-0 Champions League first-leg advantage, this match showed what Arsène Wenger's team are capable of. In that respect, it could prove one of the season's most significant games. If ever 90 minutes reminded the club's players, fans and, indeed, manager, of Arsenal's continuing potential, this was surely it.
That could have telling ramifications, not just in the fight for a Champions League qualifying place, but also for Robin van Persie's summer contract talks and Wenger's hitherto souring relationship with supporters. Those fans may now also be prepared to grant Theo Walcott more leeway. Viciously abused by his own support for much of the first half, during which Arsenal fell two goals behind, the young Englishman scored twice in the second period before leaving to a standing ovation. Confidence means everything to a player, even elite ones, and if Walcott's is repaired, club and country could benefit hugely.
Van Persie, again leading by deed and example, and Tomas Rosicky, who was simply outstanding, also scored but the key strike came, improbably, from Bacary Sagna, the full-back's fourth in 331 career matches. It was his header, five minutes prior to half-time, that transformed north London's match and mood.
It proved the first of five Arsenal goals in 28 astonishing minutes that enabled the Gunners to clamber back above Chelsea into the final Champions League qualifying place and, just as importantly for their support, within seven points of Tottenham in third. Since Spurs play Manchester United next weekend, without Scott Parker, who is suspended after being dismissed late on yesterday, the gap could shrink again. "Arsenal is alive more than anybody thought," Wenger said with barely suppressed glee.
Thirty-four minutes in, they had looked ready to be unceremoniously buried. Arsenal have been undone by injuries as much as inexperience this year. Jack Wilshere is the headline absentee but the real problems have been in defence. At the start of the season, yesterday's back four was the defence of choice, and the quartet kept clean sheets in the first two matches, against Newcastle and Udinese. Then the injuries began. This was the first time the four have been reunited since and, in that time, Wenger has fielded 26 different starting back four combinations in 41 matches, involving 14 players and nine different central defensive pairings. In the circumstances, their defensive vulnerability is hardly surprising.
Yesterday's back four had barely re-introduced themselves to each other when Emmanuel Adebayor spotted a gaping hole between the central defence and Kieran Gibbs and invited Louis Saha to run into it. Saha has been reborn since leaving Merseyside, but still does not trust his right foot and, having paused to take the ball onto his left, was fortunate his belated shot looped off Thomas Vermaelen and over Wojciech Szczesny.
Arsenal responded positively, Van Persie, twice, and Rosicky both going close to levelling. But then Modric released Bale, who touched the ball past Szczesny before ensuring his trailing leg went into the prone goalkeeper's chest. Cesc Fabregas, watching in Madrid, angrily tweeted, "they say the Spanish players dive all the time". Mike Dean was clearly not entirely convinced as he did not even caution Szczesny but the fact Arsenal retained a full complement seemed not to matter as Adebayor calmly dispatched the spot-kick.
The identity of the scorer merely confirmed the nightmare for Arsenal supporters. While their team refused to surrender it seemed one of those days, Van Persie, turning adroitly onto Walcott's flick, striking the outside of the post in the 40th minute. However, Gibbs rescued the loose ball, Mikael Arteta delivered it and Sagna beat Bale to head in. Three minutes later, Van Persie took possession 20 yards out, turned, and curled a superb shot past Brad Friedel for his 29th goal of a season. The home support, which had turned mutinous towards their own players and so crudely vituperative towards the visiting bench Harry Redknapp asked a steward to remove a fan, now cheered their players off.
Redknapp made two changes at the break, withdrawing Saha and Niko Kranjcar for Rafael van der Vaart and Sandro and switching to 4-3-3 in a attempt, he later said, to stop his team being "overrun" in midfield. It failed. Neither arrival had played in four weeks and that showed with Rosicky not only continuing to orchestrate proceedings but popping up to put Arsenal ahead with a near-post flick from Sagna's cross.
As Tottenham sought to restore parity, Walcott found redemption. After pulling his 57th-minute shot wide after being put clear by Rosicky, he did not hide, instead running the length of the pitch to be on the end of a flowing break conducted by Rosicky and Van Persie eight minutes later. His celebration revealed the strain he had been playing under and the release he felt was confirmed by the confidence of his finish when Alex Song released him behind Ledley King three minutes later.
There was time for Parker to make one late challenge too many, crunch Vermaelen's foot, and draw his second yellow, but the contest was over. The chase for north London supremacy, however, a contest that may have telling repercussions for the English game well beyond this narrow rivalry, has, like Arsenal's self-belief, been reignited.
Floodgates open: big games, big goals
* Yesterday's seven-goal derby continued this season's high-scoring meetings between the top sides.
28 Aug: Spurs 1-5 Man City
Edin Dzeko scores four in City rout.
28 Aug: Man United 8-2 Arsenal
Patched-up Arsenal side fall apart as Wayne Rooney grabs a treble.
23 Oct: Man United 1-6 Man City
City score three in stoppage time.
29 Oct: Chelsea 3-5 Arsenal
Robin van Persie's treble helps visitors recover from interval deficit.
5 Feb: Chelsea 3-3 Man United
Hosts let three-goal lead slip.
26 Feb: Arsenal 5-2 Spurs
Tottenham go two up before stunning comeback.
Arsenal: SZCZESNY 6/10; SAGNA 8; KOSCIELNY 8; VERMAELEN 7; GIBBS 6; ARTETA 7; SONG 8; ROSICKY 9; WALCOTT 8; VAN PERSIE 9; BENAYOUN 7
Tottenham: FRIEDEL 6; ASSOUEKOTTO 4; KING 4; KABOUL 4; WALKER 5; BALE 5; MODRIC 5; PARKER 5; KRANJCAR 4; ADEBAYOR 5; SAHA 5
Substitutes: Arsenal Jenkinson (Gibbs, 75), Oxlade-Chamberlain (Walcott, 81), Gervinho (Benayoun, 88). Tottenham Hotspur Van der Vaart 3 (Kranjcar, h-t), Sandro 3 (Saha, h-t), Dawson (King, 82).
Booked: Arsenal Koscielny, Arteta, Van Persie. Tottenham Modric, Parker, Sandro. Sent off: Tottenham Parker (87).
Man of the match Rosicky. Match rating 9/10.
Possession: Arsenal 56% Tottenham 44%.
Attempts on target: Arsenal 13 Tottenham 4.
Referee M Dean (Wirral). Attendance 60,106.