Chelsea held to stalemate with Arsenal at Emirates Stadium on Sunday . Arsene Wenger has not beaten Chelsea boss Jose Mourinho in 13 games . David Ospina returned to Arsenal for first time since leaving in 2011 . Oscar had to be replaced at half-time after a collision with Cesc Fabregas .
Chelsea held to stalemate with Arsenal at Emirates Stadium on Sunday . Arsene Wenger has not beaten Chelsea boss Jose Mourinho in 13 games . Cesc Fabregas returned to Arsenal for first time since leaving in 2011 . Oscar had to be replaced at half-time after a collision with David Ospina .