David Luiz was sent off as ten-man Chelsea were held at Stamford Bridge by Arsenal for the first time in six years.
The Brazil centre-back was shown am 89th-minute straight red by referee Michael Oliver, for his high challenge on Gunners’ left-back Sead Kolasinac.
It sparked angry scenes on the touchline with Carlo Cudicini, assistant to Antonio Conte, involved in a furious row with the Arsenal bench.
It also means Chelsea have now had as many reds in their last five Premier League games as they have had in their 73 games combined beforehand (three).
Earlier former Chelsea keeper Petr Cech pulled off an outstanding save to deny Pedro with the Spain winger clean through.
Aaron Ramsey blew Arsenal’s best chance when he ghosted past two players into the Blues box, only to hit the post.