London: Europa League holders Chelsea got their Champions League campaign back on track with an impressive 3-0 win over German club FC Schalke 04 while London neighbours Arsenal went down at home to last year's beaten finalist Borrusia Dortmund 1-2.
Chelsea, who were shocked at home in their first match by FC Basel, recorded their second successive win Tuesday night in the competition and went top of Group E.
Spanish striker Fernando Torres scored a brace while Eden Hazard finished the game off with a brilliant solo run.
Both Chelsea and Schalke are on six points while Basel are on four points after being held 1-1 by previously pointless Steaua Bucharest in Romania.
Arsenal lost for the first time since the opening day of the Premier League campaign after Polish striker Robert Lewandowski scored late to snatch victory for the Germans.
After three rounds of games, Dortmund tops the Group F table on goal difference from Arsenal, while Napoli also joined the clubs on six points after disposing of Marseille 2-1 in France.
Meanwhile, Barcelona had to battle hard for a 1-1 draw against AC Milan at a boisterous San Siro.
Argentina's four-time world player of the year Lionel Messi scored a fine equaliser to show he had put behind him the thigh injury that kept him out for three weeks.
Messi cancelled out Robinho's opener but, despite dominating the second half, the Catalans were unable to breach the Italians defence.
Barcelona lead Group H with a two-point advantage over Milan while Celtic kept hopes alive of reaching the last 16 with a 2-1 win at home to Ajax.
Spanish side Atletico Madrid carried on with their impressive run in the tournament, disposing off Austria Vienna 3-0 to make it three wins from three.
Highly rated striker Diego Costa was again on the scoresheet, scoring a brace.
Atletico can book a place in the knockout stages if they beat the same opponents in the next matchday.
In the same group, Zenit ran out 1-0 winners over a Porto side that played with just 10 men from the sixth minute when Hector Herrera was sent off.
Aleksandr Kerzhakov struck the winner shortly before full-time.
Atletico lead Group G with nine points while Zenit are on five and third-placed Porto on three.
Steaua Bucharest (Romania) 1-1 FC Basel (Switzerland)
At Gelsenkirchen, Germany
Schalke 04 (Germany) 0-3 Chelsea (England)
Arsenal (England) 1-2 Borussia Dortmund (Germany)
At Marseille, France
Marseille (France) 1-2 Napoli (Italy)
At Porto, Portugal
FC Porto (Portugal) 0-1 Zenit St.Petersburg (Russia)
Austria Vienna (Austria) 0-3 Atletico Madrid (Spain)
Celtic (Scotland) 2-1 Ajax (Netherlands)
AC Milan (Italy) 1-1 Barcelona (Spain)