The Costa Rica striker spent last season on-loan from Arsenal.
"Campbell was the best player in the Olympiacos team, I saw this from the first moment that I trained there," recalled Lazic to Voetbal International.
"Joel stood out.
"He can hold the ball, has a good shot, a dangerous dribble and he's lethal in one-on-one situations. But in the air, he is very strong. He is a complete striker and therefore it is not surprising that he returns to Arsenal."
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