Olympiakos boosted its hopes of reaching the Champions League knockout stages after a Brown Ideye goal helped it to a 1-0 Group F win at Dinamo Zagreb on Tuesday.
The result left Olympiakos level with Bayern Munich at the top of the section with six points from three games after the German side suffered a 2-0 setback at Arsenal. Dinamo and Arsenal have three points each.
Nigerian Ideye scored the 79th-minute winner with a superb finish from a tight angle, redeeming himself for an astonishing miss earlier in the second half.
Dinamo had the upper hand in the opening period but the best chance fell to the visitors when a viciously dipping shot by defender Arthur Masuaku forced a good save from the home team's goalkeeper Eduardo.
Dinamo pounded a series of fizzing crosses into the penalty area but to no great effect as a packed Olympiakos defense held its own.
Both sides missed a sitter each in the space of a minute shortly after the break when Dinamo's Domagoj Antolic hit the post from close range before Ideye skewed his shot wide from three meters with the goal at his mercy.
Marko Rog's trickling shot shaved the Olympiakos woodwork before Ideye raced clear of his marker on the left flank and buried the ball past Eduardo with a crisp finish.
Substitute Angelo Henriquez missed Dinamo's last chance to salvage a point, heading inches wide of the far post after a good cross from the right by full-back Alexandru Matel.