Tottenham Hotspur's Emmanuel Adebayor is sent off by Howard Webb for a foul on Arsenal's Santi Cazorla. Photograph: John Sibley/Action Images

Everything went back to that moment, 17 minutes into Tottenham Hotspur's ordeal, when Emmanuel Adebayor went hurtling into a challenge on Santi Cazorla and the dynamic of this match changed irreparably for his team. They had been winning, knocking the ball around with great confidence, but Adebayor was reckless, with his studs up, and Arsenal had their reprieve.

The red card removed their vulnerabilities long enough to instigate a wild and eccentric Arsenal win that will go a long way to soothing the mood at the Emirates after a difficult period for Arsène Wenger's team. Spurs, for long spells, were in disarray. They have lost four of their past five league fixtures and, though Adebayor will have to shoulder the responsibility, it must have been alarming for André Villas-Boas to see the way his team crumpled. It was the same margin of victory as when these sides met last season and the away section was virtually empty before the end. Tottenham's fans had seen enough.

For Adebayor, what words does he find to cover an apology? He had given his team a lead, his 10th goal in his 12 north London derbies, but his place in the rivalry between these clubs will always be remembered for its infamy rather than his finishing skills. Maybe it was the adrenaline of facing his former club, and all the spiteful history that goes with it. Perhaps he had become too pumped-up after his 10th-minute goal, with a hostile crowd booing every touch. Whatever the reason, it was a dereliction of duty that had grave consequences for his club.

Arsenal equalised within six minutes through Per Mertesacker's header and Spurs, a man down, were dangerously close to a full-on capitulation before clearing their heads at the break. Lukas Podolski's scuffed effort gave the home side a 42nd-minute lead, aided by a deflection off William Gallas, and Olivier Giroud swept in their third after some fine work from Cazorla in stoppage time.

Cazorla added the fourth on the hour, firing in at the far post after Podolski's low centre, and it is a measure of the way the match went for long spells that Hugo Lloris could be forgiven for coming off the pitch thinking he had justified his selection ahead of Brad Friedel in the Spurs goal. The France international, increasingly frustrated recently by his lack of games, was horribly exposed at times but made half a dozen splendid saves to prevent the rout getting out of hand. He and Gareth Bale emerged in credit for Spurs, but very few others did.

Arsenal were rampant in those moments, playing expansive, refined football, with Theo Walcott a constant menace on the right, Giroud looking confident and Cazorla at the hub of just about everything. Yet, conversely, this was still an Arsenal performance riddled with flaws.

To begin with, their performance has to be measured by the generosity of their opponents and the mistakes that led to some of the goals. These were individual moments that could not all be pinned on Adebayor. Kyle Naughton will wince when he sees how easily Walcott got past him to cross for Mertesacker's equaliser. Steven Caulker was missing after picking up an injury on England duty and their lack of marking, again highlighted in Arsenal's first goal, was a recurring theme.

Wenger must have been troubled as well to see some of the old failings return after one of Bale's surging runs, finished with a right-foot shot, had made the score a little less harrowing at 4-2. Two goals ahead, against a team with 10 players, it was bizarre to see how nervous Arsenal and their crowd became in the final exchanges. The entire mood shifted and Spurs fed off it. Briefly, there was the sense, with Bale driving forward and Arsenal looking jittery in defence, that the away side might force an implausible result.

Those moments emphasise the ramifications of Adebayor's dimwittedness and what might have been if Spurs had a full XI on the pitch. They had controlled the early stages and discovered, very quickly, that Arsenal's defence still has the habit of creating its own problems. In the 10th minute Jermain Defoe eluded Mertesacker far too easily, running on to Jan Vertonghen's long ball. Wojciech Szczesny stretched out a hand to the initial shot but Adebayor knocked in the rebound.

Unfortunately for Spurs, the striker's most significant contribution to the game was yet to come. This was his fourth red card in English football and the third that Howard Webb has shown him. Adebayor might have known to take a little care on the back of that sequence but still went flying in to Cazorla, catching him mid-air and prompting a little shoving match between Jack Wilshere and Bale. Webb got the decision right, on the basis that it was reckless.

At 1-0, Aaron Lennon put one shot just past the far post. Gallas had already curled the ball into the top corner only for the goal to be disallowed, correctly, because he was offside. Villas-Boas seemed to have devised the right system, emboldened enough to start with Defoe and Adebayor in attack for the first time this season in the league.

The Spurs manager employed a 3-5-1 formation for the second half but Cazorla punished them again, with more fine work from Walcott in the buildup, and when Bale's goal encouraged the visitors to go forward it was inevitable there would be gaps for Arsenal to exploit. Walcott had played with enough menace for Villas-Boas to withdraw Naughton at half-time and the winger was even more dangerous after the break. Alex Oxlade-Chamberlain, on for Giroud, played the pass. Walcott stroked his shot past Lloris and the rout was complete.