Nacho Monreal: Did well against Willian, but unable to make much of an impact. 5. Per Mertesacker: Sent off after being caught on the wrong side of Diego Costa after just 18 minutes. 3. Laurent Koscielny: Steady, but fortunate to avoid conceding a penalty for a body-check on Cesc Fabregas. 5. Mathieu Flamini: Missed a gilt-edged chance to equalise on the stroke of half-time and another late in the game. 5. Aaron Ramsey: Tried to impose himself on proceedings, but support was lacking. 7. Mesut Ozil: A subdued performance from the mercurial German. 6. Olivier Giroud: Withdrawn after Mertesacker’s dismissal, a decision booed by the home supporters. 5. Theo Walcott: Captain for the day, 10 years after signing for the Gunners, made the linesman work more than Chelsea’s defence. 5. Press Association Joel Campbell: Showed flickers of danger for the Gunners. 6. SUBSTITUTES: Gabriel (for Giroud, 22 minutes): Allowed Costa in at the near post to score. 5. Alexis Sanchez (Campbell, 57): Attempted to rejuvenate the Gunners, but ran out of support. 6. Alex Oxlade-Chamberlain (Walcott, 75): Provided fresh legs but could not find the breakthrough. 5. CHELSEA: Thibaut Courtois: Barely called upon by the 10 men of Arsenal. 6. Branislav Ivanovic: A disciplined performance from the man who this week signed a new contract. 6. Cesar Azpilicueta: Kept Arsenal’s wing-men quiet and provided an option down the left. 6. Kurt Zouma: Another solid display against the Gunners from the Frenchman. 7. John Terry: Resolute against Arsenal’s short-handed attack. 7. Nemanja Matic: A few stray passes and still not the dominant performer of last season. 5. John Obi Mikel: Did what is expected of him, including a clumsy challenge on Sanchez. 6. Oscar: Still to find a consistent level of performance. This was another quiet one. 5. Diego Costa: Troubled Arsenal without playing football in the reverse fixture; this time he excelled. 8. Cesc Fabregas: The boos appeared to spur on the former Gunners captain in a display full of guile. 8. Willian: Collective performances are improving, but the Brazilian remains one of the brightest players no matter what. 7. SUBSTITUTES: Loic Remy (for Costa, 68): Offered fresh legs and an outlet, but the tide was going the other way. 5. Eden Hazard (for Oscar, 77): Had little chance to impress on his return from a groin injury. 5. ARSENAL: Petr Cech: Made some good saves against his former employers. 7 (out of 10). Hector Bellerin: His forays forward were tempered by the sending off. 5.