Olivier Giroud struck two minutes after coming on as a substitute and Mesut Ozil scored with almost the last kick of the game to give Arsenal a 2-0 win over Bayern Munich and kickstart their Champions League campaign.
Giroud replaced Theo Walcott after 75 minutes and headed in a Santi Cazorla header from close range in the 77th minute after the otherwise superb Manuel Neuer flapped at the ball to put Arsenal on their way to their first win after losing their opening two games.
Ozil scored with virtually the final kick when his shot just crossed the line before being scooped out of the goal by his World Cup-winning team mate Neuer.
The result ended Bayern's run of 12 successive wins in all competitions and kept Arsenal in the fight though still with just three points. Bayern and Olympiakos Piraeus have six points.
Meanwhile, two goals from Ivan Rakitic gave Barcelona a comfortable 2-0 victory away to BATE Borisov and consolidated their position at the top of Champions League Group E.
|Barcelona are three points clear of Leverkusen at the top of the group [EPA]
Rakitic, who came on following an injury to Sergi Roberto after just 17 minutes, hit a sublime strike into the top corner having been set up by Neymar at the start of the second half.
Neymar was again the provider after 64 minutes for Rakitic who sealed the win with a clinical finish past keeper Sergey Chernik. Barca have seven points from three games and BATE have three.
Elsewhere, Chelsea struck the woodwork twice but could not find a breakthrough in an entertaining 0-0 Champions League draw at Dynamo Kiev that left everything to play for in Group G.
Within the context of Chelsea's poor start to the season, a goalless draw in the Ukraine can be considered a positive result and Jose Mourinho's side certainly did enough to earn all three points.
BATE Borisov 0-2 Barcelona
Bayer Leverkusen 4-4 AS Roma
Dynamo Kiev 0-0 Chelsea
Porto 2-0 Maccabi Tel Aviv
Valencia 2-1 Ghent
Zenit St Petersburg 3-1 Olympique Lyon
Arsenal 2-0 Bayern Munich
Dinamo Zagreb 0-1 Olympiakos Piraeus