Mario Balotelli gave Nice an early lead, but it was not enough to prevent Lazio from emerging 3-1 winners at the Stade de Nice on Thursday.
Cologne's seemingly cursed start to the Bundesliga continued when Stuttgart scored in the fourth minute of injury time for a 2-1 win.
Bayern Munich lost a two-goal lead for the second successive week to draw 2-2 at Hertha Berlin's Olympiastadion.
Kevin Volland scored twice as Bayer Leverkusen returned to winning ways with a comfortable 3-0 Bundesliga victory over Hamburg at BayArena.
Borussia Dortmund leapfrogged Bayern Munich back into top spot in the Bundesliga following a 3-0 win at Hamburg.
Borussia Dortmund went to the top of the Bundesliga table as they beat Cologne 5-0 at Signal Iduna Park.
Cologne have criticised "inadequate" security measures at the Emirates after crowd issues in their Europa League tie with Arsenal.
UEFA has opened disciplinary proceedings against Arsenal and Cologne following incidents at the Europa League match on Thursday.
Arsenal will hold their own investigation into disturbances after five arrests were made following crowd trouble against Cologne.
Alexis Sanchez's fine strike helped Arsenal to a 3-1 win over Cologne in the Europa League, after the match was delayed by an hour.
Arsene Wenger praised the "exceptional" Alexis Sanchez after his fine goal helped Arsenal to a 3-1 Europa League win over Cologne.
Arsene Wenger admits he thought Arsenal's Europa League game against Cologne would be called off after crowd issues.
Cologne fans marched through central London this afternoon ahead of tonight's Europa League tie against Arsenal.
Arsenal's Europa League clash with Cologne at the Emirates was delayed by an hour over a "crowd safety issue".
Alexis Sanchez starts for Arsenal as they host Cologne, but kick-off is delayed for an hour in the "interests of crowd safety".
Mark Uth netted twice as defending champions Bayern Munich slumped to a shock 2-0 defeat at Hoffenheim on Saturday.
Alexis Sanchez and Jack Wilshere both trained on Wednesday and could be involved in Arsenal's opening Europa League match.
Arsenal have been drawn with BATE, Cologne and Red Star Belgrade in the Europa League, while Everton face Lyon, Atalanta and Apollon Limassol.
Borussia Monchengladbach kicked off their new Bundesliga campaign with a 1-0 home win over rivals Cologne.
Luca Waldschmidt's late winner condemned Wolfsburg to Bundesliga's relegation play-off as Hamburg survived on the final day.
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