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There was plenty of attacking intent from both sides early on, with speculative forays forward and a number of prickly challenges punctuating the first few minutes of the game.
Olympiacos were responsible for the first concrete chance of the game just before the quarter-hour mark when Alberto Botia was first to a free kick, jumping high and sending a towering header inches wide of the right-hand post.
The hosts were next to threaten when, 19 minutes in, Junior Fernandes produced a ferocious strike from the edge of the box, but Roberto Jimenez pulled off an acrobatic reflex save to keep the ball out.
Both sides continued to labour in the final third as the game went on, with many efforts either flying high into the stands or safely into the arms of the opposition goalkeepers.
Arthur Masuaku tested Eduardo in the 32nd minute with a powerful strike following an incisive through-ball, while Brown Ideye wasted a great chance four minutes later when his header from near the penalty spot soared high above the crossbar.
Nevertheless, neither team could break the deadlock by the break, leaving the referee to blow the half-time whistle with both sides all square and their clean sheets still intact.