Arsenal light up Wenger's 17th anniversary as manager

Arsenal's German midfielder Mesut Ozil (L) celebrates scoring the opening goal against SSC Napoli at the Emirates Stadium, North London. (AFP/Adrian Dennis)

First-half goals by record signing Mesut Ozil and in-form Frenchman Olivier Giroud, his sixth this season and coming a day after his 27th birthday, gave the Gunners their 10th successive win.

While they took a firm grip on their group with six points from two games, London rivals Chelsea got their campaign back on track, after an embarrassing opening home defeat to Basel, with a 4-0 rout of Romanian side Steaua Bucharest.

Elsewhere Barcelona have a firm grip on their group with maximum points after a 1-0 win over a gallant Celtic, who played the last half hour with just 10 men as captain Scott Brown was sent off.

Barca have a two-point lead over AC Milan, who face them next in a double header, after the Italian side salvaged a 1-1 draw in Amsterdam with a Mario Balotelli penalty four minutes into stoppage time.

Barca's Spanish rivals Atletico Madrid displayed the grittiness that their coach Diego Simeone displayed during his playing career to come back and beat Porto 2-1 away and top their group on six points, leaving them unbeaten on the field of play this season.

Arsenal hold a three-point lead over both Napoli and last season's beaten finalists Borussia Dortmund, who beat Marseille 3-0 and will provide a stern test for Wenger's men in the upcoming double header.

Polish striker Robert Lewandowski gave them an early lead, finishing off a brilliant move by the German league leaders.

Marseille goalkeeper Steve Mandanda was badly at fault for Dortmund's second in the second-half as apparently transfixed by the players rising in front of him, he allowed Marco Reus's long range freekick to beat him and cross the line.

Lewandowski, who is widely expected to sign for Dortmund's bitter domestic rivals Bayern Munich for next season, got a second as he slotted home a penalty with 10 minutes remaining.

Chelsea recovered from an early blow of Fernando Torres limping off -- to be replaced by Cameroon veteran Samuel Eto'o -- as Brazilian Ramires gave them the lead in the 19th minute.

Andre Schurrle was especially eyecatching for Chelsea, but it was Eto'o who played a role in the second goal a minute before half-time as his shot was saved, but the rebound went into the net off Steaua player Daniel Georgievski.

Ramires doubled his tally in the 55th minute and the rout was completed by Frank Lampard in the final minute of normal time.

Chelsea next face two games in succession against Schalke, who will go into the first match top of the group thanks to impressive young German international Julian Draxler's second-half goal that saw off Basel 1-0 in Switzerland.

The game had been stopped in the first-half due to a group of environmental protestors abseiling from one of the stands.

Barcelona struggled to impose themselves on Celtic but their task was considerably eased when Brown was sent off for bringing Neymar down on the hour mark.

Sure enough Barcelona eventually cracked the Celtic defence as Alexis Sanchez's cross was brilliantly headed into the far corner by Cesc Fabregas with 15 minutes remaining.

Porto's prolific Colombian marksman Jackson Martinez gave Porto a first-half lead but Atletico fought back to win with second-half goals by Uruguayan international Diuego Godin and Turkish international Arda Turan.

European Champions League results:

Group E
Basel (SUI) 0 Schalke (GER) 1
Steaua Bucharest (ROM) 0 Chelsea (ENG) 4

Group F
Arsenal (ENG) 2 Napoli (ITA) 0
Borussia Dortmund (GER) 3 Marseille (FRA) 0

Group G
FC Porto (POR) 1 Atletico Madrid (ESP) 2
Zenit Saint Petersburg (RUS) 0 Austria Vienna (AUT) 0

Group H
Ajax (NED) 1 AC Milan (ITA) 1
Celtic (SCO) 0 Barcelona (ESP) 1