Ieroklis Stoltidis scored an injury-time winner as Olympiakos beat Standard Liege 2-1 in the Uefa Champions League.
|Olympiakos players celebrate their late winner [AFP]
Standard went ahead in the 37th minute when Igor De Camargo ran through the Olympiakos defense and drove home a pass from Serb striker Milan Jovanovic.
It was the first goal Olympiakos had conceded at home this season.
Argentine winger Luciano Galletti kept the visitors under pressure and set up the equaliser in the 43rd minute.
Costas Mitroglou headed in his free kick, lobbing over goalkeeper Sinan Bolat.
Olympiakos missed a string of late chances before substitute Stoltidis headed in the winner.
"We both had chances and it could have gone either way,'' Stoltidis said.
"But toward the end of the match we really tried hard for a goal. We had a few good chances before we got the goal at the end.
"The points we got are really valuable ... in the final minutes of the match, the players really went all-out. I'm optimistic the team is getting better and better.''
Olympiakos has six points in Group H, five more than Standard. Arsenal leads with seven points after drawing 1-1 with AZ Alkmaar, which has six points.
The Greek champions missed Brazilian striker Diogo through injury.
Defender Vassilis Torosidis, who is recovering from a virus infection, was kept on the bench.
In the second half, the hosts pressed hard for the win but had a scare in the 69th minute when Jovanovic hit the crossbar with a powerful left-footed shot that beat goalkeeper Antonis Nikopolidis.
Olympiakos' Dudu had a goal disallowed in the 83rd, pushing De Camargo to the ground before putting the ball in the net. Enzo Maresca followed up with a powerful shot four minutes later that was stopped by an impressive save from Bolat.
Stoltidis scored the winner only seconds before Portuguese referee Pedro Proenca ended the match.
It was the second home win in the group for Olympiakos after having beaten AZ Alkmaar 1-0.
"The crowd was amazing. This victory belongs to them,'' Olympiakos coach Zico said.
"I was happy with the players and only needed one substitution (Stoltidis). The players were hungry for the good result and worked hard to create chances. Qualification is now in our hands.''
AZ Alkmaar pinch late point against Gunners
Group H's other match saw AZ Alkmaar midfielder David Mendes da Silva scor in the last minute of stoppage time to salvage a 1-1 draw for his side against Arsenal.
Andrei Arshavin and Robin van Persie had combined to set up Cesc Fabregas, who gave Arsenal the lead with a low shot in the 36th. But Graziano Pelle's header in the final seconds found da Silva, who volleyed home from close range to stun Arsenal and end the English club's perfect start in Group H.
Arsenal has seven points from three games, while AZ has two.
"This is a morale-boosting draw for us,'' AZ captain Stijn Schaars said.
"You have to be realistic, Arsenal is a very good team with a a lot of quality, so it feels nice to get a draw against them.''
Van Persie got an early chance to put Arsenal ahead from eight metres but the former Feyernoord forward saw his ninth-minute shot blocked by AZ goalkeeper Sergio Romero.
Wearing shirts with no logo after main sponsor DSB Bank NV was recently declared bankrupt, AZ enjoyed superior ball possession in the first half.
But it failed to create any meaningful chances until the 25th, when striker Mounir El Hamdaoui fired wide from the edge of area.
Arsenal responded two minutes later with Emmanuel Eboue setting up Arshavin, but the Russian's close-range effort went over the bar.
Arshavin then stole the ball from defender Niklas Moisander and released it to van Persie, who crossed the ball for Fabregas to slot in.
Romero kept AZ in the game with a save in the 42nd, parrying van Persie's long-range shot.
Romero also made a diving save to deny van Persie's curling free kick in the 50th.
Arshavin could have doubled Arsenal's advantage, but his 89th-minute shot was saved by Romero.
With Arsenal looking set to come away with another away win, Schaars flighted the ball into the Arsenal area and found Pelle, whose goal-bound header was converted by da Silva.