Alexis Sanchez put his off-field problems aside to help Arsenal kick off their Europa League Group H campaign with a 3-1 over Cologne following a one-hour delay due to crowd congestion.

Sanchez has cut a frustrated figure this season having seen a move to Manchester City fall through, but his moment of quality proved decisive on a bizarre Thursday night at the Emirates Stadium.

The game began amid swirling controversy, having been put back 60 minutes after a reported 20,000 Cologne fans descended on London despite only 3,000 tickets being available.
 
It appeared several were also in the Arsenal end, and they were quickly sent into raptures when Jhon Cordoba opened the scoring with a stunning 40-yard strike after nine minutes.

A lifeless atmosphere among the home contingent, depleted in numbers presumably because some fans opted to return home, was invigorated after the break as substitute Sead Kolasinac levelled.

And Arsenal ultimately condemned Cologne to defeat in their first European outing for 25 years thanks to Sanchez and Hector Bellerin's first goal of the campaign.

Any concerns the game may not go ahead would have been justified at one stage, with riot police inside and outside the stadium following the decision to delay kick-off.
 
But Arsenal suggested they were "comfortable" with the situation despite incidents of crowd trouble and the contest finally got under way at the revised time of 21:05pm BST.
 
Within 10 minutes, the hosts were anything but comfortable.
 
A hopeful long ball from Lukas Klunter had David Ospina racing from his line, but the Arsenal goalkeeper could only clear as far as Leonardo Bittencourt. 
 
The midfielder made a hash of an attempt to control and the ball fell to Cordoba - who unleashed a stunning strike that flew over the back-pedalling Ospina and found the net.
 
The hosts had actually been on top prior to that intervention, a pattern that continued after the goal as Olivier Giroud twice went close.

Arsene Wenger introduced Kolasinac at half-time and the move paid immediate dividends as he hammered Arsenal level.

Theo Walcott got in behind the defence and, after his attempted pass deflected off Klunter and into the air, the left-back was on hand to unleash an unstoppable volley.

Arsenal should have taken the lead in the 64th minute, but Ainsley Maitland-Niles was 
denied by the hand of Timo Horn when trying to round the keeper.

He could do nothing soon after, though, as Sanchez cut in from the left wing and gradually worked an opening to unfurl a wonderful curler into the corner from 20 yards.

The visitors responded well, with Cordoba offering a reminder of his threat when forcing Ospina into action.

But, after Sanchez went close again, Arsenal wrapped up the points when Bellerin slid home on the rebound after Walcott's effort was saved.

Full Results:
  
Group A

Slavia Prague (CZE) 1 (Necid 12) Maccabi Tel Aviv 0
Villarreal (ESP) 3 (Sansone 16, Bakambu 75, Cheryshev 77) Astana (KAZ) 1 (Logvinenko 68)
                  
Group B

Young Boys (SUI) 1 (Fassnacht 14) Partizan Belgrade (SRB) 1 (Jankovic 11)

Dynamo Kiev (UKR) 3 (Sydorchuk 47, Junior Moraes 49, Mbokani 65-pen) Skenderbeu (ALB) 1 (Muzaka 39)
                  
Group C

Istanbul Basaksehir (TUR) 0 Ludogorets (BUL) 0

Hoffenheim (GER) 1 (Wagner 24) Braga (POR) 2 (Joao Carlos 45+1, Dyego Sousa 50)
                  
Group D

Rijeka (CRO) 1 (Elez 29) AEK Athens (GRE) 2 (Mantalos 16, Christodoulopoulos 62)

Austria Vienna (AUT) 1 (Borkovic 47) AC Milan (ITA) 5 (Calhanoglu 7, Andre Silva 10, 20, 56, Suso 63)
                  
Group E

Apollon Limassol (CYP) 1 (Sardinero 90+3) Lyon (FRA) 1 (Depay 53-pen)

Atalanta (ITA) 3 (Masiello 27, Gomez 41, Cristante 44) Everton (ENG) 0
                  
Group F

Copenhagen (DEN) 0 Lokomotiv Moscow (RUS) 0

Zlin (CZE) 0 Sheriff Tiraspol (MDA) 0
                  
Group G

FCSB (ROU) 3 (Budescu 21-pen, 44, Alibec 72) Viktoria Plzen (CZE) 0

Hapoel Beer Sheva 2 (Einbinder 2, Tzedek 60-pen) Lugano (SUI) 1 (Tzedek 67-og)
                  
Group H

Red Star Belgrade (SRB) 1 (Radonjic 54) BATE Borisov (BLR) 1 (Signevich 72)
                  
Group I

Vitoria Guimaraes (POR) 1 (Pedrao 25) Salzburg (AUT) 1 (Valon Berisha 45)
Marseille (FRA) 1 (Rami 48) Konyaspor (TUR) 0
                  
Group J

Hertha Berlin (GER) 0 Athletic Bilbao (ESP) 0

Zorya (UKR) 0 Ostersund (SWE) 2 (Ghoddos 50, Gero 90+4)
                  
Group K

Vitesse Arnhem (NED) 2 (Matavz 33, Linssen 57) Lazio (ITA) 3 (Parolo 51, Immobile 67, Murgia 75)

Zulte Waregem (BEL) 1 (Leya Iseka 46) Nice (FRA) 5 (Plea 16, 20, Dante 28, Saint-Maximin 69, Balotelli 74)
                  
Group L

Real Sociedad (ESP) 4 (Llorente 9, 77, Zurutuza 10, Skjelvik 41-og) Rosenborg (NOR) 0

Vardar (MKD) 0 Zenit (RUS) 5 (Kokorin 6, 21, Dzyuba 39, Ivanovic 66, Rigoni 89)