Gabriel and Santi Cazorla were both sent off as Arsenal were beaten 2-0 by Chelsea in a heated contest at Stamford Bridge.
The major talking point of the game came at the end of the first half when Gabriel and Diego Costa were both booked after clashing in the area.
Gabriel was then dismissed by referee Mike Dean moments later for appearing to flick his leg at Costa as they retreated to the halfway line, sparking an angry response from the defender.
The Premier League champions made their numerical advantage count in the 52nd minute as Kurt Zouma headed home from Cesc Fabregas' free-kick.
And, after Cazorla was shown a second yellow card, Eden Hazard secured Chelsea's first home league win of the season in the dying stages as his shot deflected past Petr Cech.
The defeat caps off a disappointing week for Arsenal following their Champions League loss to Dinamo Zagreb and their frustration will only be compounded by the controversial dismissal of Gabriel.
While Jose Mourinho and Arsene Wenger shook hands before the match, the Arsenal boss headed straight down the tunnel at the final whistle as Mourinho embraced John Terry, who had been left out of the starting line-up.
Branislav Ivanovic captained the side in his absence while Theo Walcott started for the visitors ahead of Olivier Giroud.
The game started in lively fashion as Aaron Ramsey had a shot blocked and Fabregas saw an effort saved by Cech, playing at Stamford Bridge for the first time since his summer move to Arsenal.
Walcott forced Asmir Begovic into a low save at the other end but the hosts started to dominate possession as the half wore on.
Pedro got behind the Arsenal defence but was unable to get the ball under control before having a shot from the edge of the box that Cech pushed away.
The main talking point of the half came in the final few minutes though.
It all started when Costa and Koscielny clashed in the box, with the striker putting two hands to the face of the defender and then hitting him with a swinging arm.
Gabriel became involved in the heated exchange and was booked along with Costa by the referee.
But worse was to follow for the visitors as Gabriel was dismissed for flicking a leg out at Costa as the two players walked back to the halfway line.
Gabriel reacted furiously to the decision and had to be held back from confronting Costa while Wenger waited for the referee and then followed him down the tunnel as he walked off for half-time.
Wenger's tactical response was to take off Francis Coquelin and bring on Calum Chambers, but the 10-man Gunners could not hold out for long in the second half.
Fabregas curled a free-kick into the box and Zouma arrived unmarked at the back post to head past Cech.
With a numerical advantage, the home side dominated possession and Hazard tested Cech with a shot from the edge of the area.
Arsenal could have levelled, though, as Alexis Sanchez latched onto a ball over the top but missed the target from close range.
The miss would prove costly as Chelsea took control of the game and were handed even more of an advantage when Cazorla was shown a second yellow for catching Fabregas in the 79th minute.
Hazard then wrapped up victory in the final few minutes with a shot that deflected past Cech.
Chelsea: Begovic (7), Ivanovic (6), Zouma (8), Cahill (7), Azpilicueta (7); Matic (7), Fabregas (7); Pedro (7), Oscar (7), Hazard (7); Diego Costa (7).
Subs: Mikel (6), Ramires (6), Remy (6).
Arsenal: Cech (6), Bellerin (6), Gabriel (5), Koscielny (6), Monreal (6) Coquelin (6), Cazorla (6), Ramsey (6), Ozil (6), Alexisn (7), Walcott (6).
Subs: Chambers (7), Oxlade-Chamberlin (6), Giroud (6).
Man of the match: Kurt Zouma