The Brazilian was uncomfortable with the perceived French connection...
Particularly drawing the ire was Arsenal's second goal, with Andrei Arshavin tapping-in from a clearly offside position. The goal sealed the game just when Olympiakos were searching for a late equaliser.
"We had three French referees with a French coach [Wenger] in the other team [Arsenal] that had 10 French players," Zico said, according to BBC. "Maybe we could have had referees from other countries."
Asked if he thought there was intentional bias, the tactician replied: "I don't think they were biased. We always hope it's a mistake."
The Brazilian, who has only been in charge of the Greek champions for a fortnight after replacing outgoing manager Temuri Ketsbaia, felt his side had paid the price for a busy schedule.
"We would have liked to have left with a better result, but Arsenal are one of the best teams at the moment," he said.
"Our fifth game in less than 15 days affected our performance in the last 10 minutes."
Olympiakos and former Aston Villa defender Olof Mellberg also expressed his disappointment that Arshavin's goal was allowed to stand.
"They scored a goal which was at least three yards offside," Mellberg said. "You can't understand how a linesman can miss a goal like that."
Philip Wen, Goal.com UK