Gabriel Magalhaes scored the only goal of the game as Arsenal beat Tottenham in the Premier League’s first north London derby of the season.
After both team had wasted chances in the first-half, Gabriel nodded in from a corner as set-piece issues continued to undermine Spurs.
With an away tie at Manchester City in seven days, Arsenal's fixture at their rivals was already being described as a make-or-break game in their quest to be champions following a home draw against Brighton prior to the international break.
But without key duo Martin Odegaard and Declan Rice, the Gunners secured all three points following Gabriel's 64th-minute goal to stake their title credentials and leave Spurs with just one win so far this term.
Odegaard and Rice were absent from Arsenal's midfield, with the former sidelined by an ankle injury and the latter banned following his red card against Brighton. Jorginho took over from Rice as Leandro Trossard was tasked with filling Odegaard's role as the team's conductor.
For Tottenham, Micky van de Ven was back from injury, with summer signing Dominic Solanke leading the attack after missing two games with an ankle problem.
And the former Bournemouth man was involved instantly when he wriggled free in the Arsenal penalty area before finding Son Heung-min, whose pull-back to Dejan Kulusevski produced a fine save from David Raya.
On the other side of the pitch, Kulusevski's cross then split the Arsenal defence with Raya again called into action.
Spurs were in the ascendancy, and Ben White - who along with his Arsenal team-mates were dressed in black as the Gunners contested a north London derby for the first time in almost four decades not in their traditional red due to a kit clash - saw his blushes spared with 15 minutes gone.
White was pounced on by Son who found Solanke in the area, but the England international was not quick enough on the uptake. William Saliba did not need a second invitation to dispossess him when Solanke really should have done better.
Moments later, Saliba then found his name in referee Jarred Gillett's book for failing to return the ball after a foul on Solanke. It was the first of seven bookings of a fiercely contested first period.
The hosts were the quickest out of their marks, but as the half wore on Arsenal came into the game. Kai Havertz's header from Gabriel Martinelli's cross was well-saved by Guglielmo Vicario before the Brazilian should have put the Gunners ahead.
Trossard's exquisite through-ball put Martinelli one-on-one with Vicario, but the winger's effort was tame and his weak effort was comfortably gobbled up by the Spurs keeper. Cue a furious Mikel Arteta on the touchline.
Jurrien Timber's challenge on Pedro Porro then sparked a brawl on the touchline with both the Arsenal defender and Vicario front and centre. Both men were booked but Timber escaped a red card for going over the top of the ball following a VAR check. Honours even at the break.
The hour mark arrived with Van de Ven's header - straight down Raya's throat from a James Maddison cross - the only real chance of the second period up to that point.
Arsenal looked threatening on the counter-attack with Martinelli and Havertz linking up to put Bukayo Saka through. His shot was deflected behind off Porro, and from the ensuing corner came the breakthrough.
Gabriel ghosted off Cristian Romero, and with Vicario blocked off, the Brazilian headed home unmarked from a handful of yards out. It was Arsenal's 23rd goal from set-pieces since the start of last season - more than any club in the league.
Spurs, for all their encouraging work, appeared stunned by Gabriel's goal and the frustration among the majority of the home fans started to show.
But Spurs have been the masters of late goals in front of their own supporters during the Ange Postecoglou era, and they wanted a penalty with eight minutes remaining when Gabriel took the ball off Solanke, but Gillett waved away their appeals.
Pape Sarr then miscued his shot wide and Arteta's side, with Raheem Sterling handed his debut from the bench, were content to soak up the pressure.
Kulusevski came closest to finding an equaliser but his long-range effort fizzed agonisingly over the bar as Arsenal saw out five minutes of injury time to claim three successive derby wins at Tottenham for the first time since 1988.
