The Gunners looked crushed once Jorginho fired Chelsea ahead from the penalty spot when Luiz was shown a straight red card for bundling over Tammy Abraham.
The Chelsea forward had pounced on a terrible backpass by Shkodran Mustafi and rounded keeper Bernd Leno once he was shoved over by Brazil defender Luiz.
Chelsea were dominant for long periods however did not kill the game off and were disciplined once N’Golo Kante slipped within the centre circle allowing 18-year-old Martinelli to gallop free and produce a superb finish, the Brazilian’s tenth league and cup goal of the season.
It was Arsenal’s 1st shot on target and came after a Chelsea corner that was cleared by Mustafi, the German atoning for his earlier error.
Chelsea thought that they had won it once skipper Cesar Azpilicueta scored from six yards six minutes from time however spirited Arsenal earned a point through captain Hector Bellerin – making his 1st appearances since five Dec.
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