Mikel Arteta has admitted Arsenal were "far from our standards" in the second half against Slavia Prague, despite securing a 2-1 Champions League victory to claim their third win in four matches.
Andoni Iraola was left frustrated after Liverpool threw away the lead twice before suffering a 3-2 Champions League defeat against Fenerbahce in Istanbul on Wednesday.
Borussia Dortmund picked up all three points with a 2-1 victory over Real Betis in the Champions League on Wednesday night.
Arsenal maintained their impressive Champions League away record with a 2-1 victory over Slavia Prague on Wednesday, but manager Mikel Arteta warned that his team still has plenty to learn after a nervous finish in the Czech Republic.
Federico Valverde struck a stunning stoppage-time winner as Real Madrid came from behind to down AEK Athens and maintain their unbeaten record in this season's Champions League.
Erling Haaland scored a late winner as Manchester City claimed a thrilling 3-2 victory over RB Leipzig in the Champions League on Wednesday, but the striker warned his team they must improve if they want to compete for major trophies.