Paris - Olivier Giroud scored a fantastic late winner as Arsenal edged to their third straight Europa League win by beating 10-man Red Star Belgrade 1-0 in Serbia on Thursday.
Arsene Wenger's men rode their luck at times in an uninspiring performance, before Giroud struck in the 85th minute after Red Star had seen Milan Rodic sent off.
The Premier League side stay top of Group H, five points clear of Red Star, while Cologne remained pointless after losing 1-0 at BATE Borisov.
Wenger made sweeping changes to his team with Sunday's Premier League visit to Everton in mind.
Only goalkeeper Petr Cech remained from the starting XI that lost 2-1 at Watford last weekend, as injury-plagued French right-back Mathieu Debuchy made his first start for the club in 11 months.
Roared on by a vociferous home crowd, Red Star made a bright start, but it was Arsenal winger Theo Walcott who saw the game's first real chance saved by the legs of Canadian goalkeeper Milan Borjan.
The inexperienced away defenders were lucky not to concede in the 26th minute when Richmond Boakye headed onto the crossbar when unmarked at a corner.
Arsenal were struggling to cope with the pace in the Serbians' attack and Cech was forced into a low save to deny Nemanja Radonjic before half-time.
The visitors started the second period with more urgency, as Giroud fired over and Walcott saw his shot smothered by Borjan after being released by Jack Wilshere's through ball.
Arsenal were given a great chance of snatching all three points when home defender Rodic was given a second yellow card with 10 minutes to play.
The Londoners took it in style with a wonderful goal, as Wilshere's clever flick was turned across goal by Walcott for Giroud to send an overhead kick spinning into the top corner.
Italian Serie A high-flyers Lazio came from behind to win 3-1 at Nice.
Mario Balotelli opened the scoring for Nice in the fourth minute, after announcing the birth of his son Lion earlier this week, only for Felipe Caicedo to equalise seconds later.
The Italian capital-city side took top spot in Group K as midfielder Sergej Milinkovic-Savic scored a second-half brace.
Real Sociedad bounced back from their 3-1 defeat by Zenit St Petersburg last time out with a 6-0 thrashing of Vardar in Macedonia as Brazilian Willian Jose scored four goals in 25 minutes.
The La Liga outfit are second in Group L, three points behind Zenit after Roberto Mancini's Russians saw off Rosenborg 3-1.
Athletic Bilbao, Europa League runners-up to Atletico Madrid in 2012, are third in Group J on only two points after being held to a 2-2 draw at Swedish club Ostersund, despite a late leveller from Inaki Williams.
Swiss outfit Lugano picked up their first ever group-stage points in a European competition with a 3-2 victory over Czechs Viktoria Plzen in Group G, while Marseille warmed up for Sunday's clash with arch-rivals Paris Saint-Germain by beating Vitoria Guimaraes 2-1.