Mario Mandzukic scored seven minutes before the break to give Atletico Madrid a half-time lifeline after they had fallen two behind to Olympiacos in Athens.
The Spanish champions had seen their Champions League kickoff gatecrashed by an exiled La Liga star, as Ibrahim Affelay helped the Greeks to a two-goal advantage after half an hour of the Group A tie.
The manner of the first goal was strangely out of character for Atletico as they fell asleep at a corner kick.
Olympiacos took it short and Barcelona loanee Affelay laid the ball off for Arthur Masuaku, a summer signing from Valenciennes, to fire left-footed into the bottom corner for his first goal for the club.
The Dutchman then added his own name to the scoresheet by beating deputy Atletico keeper Jan Oblak in the same part of the goal, after a Mario Suarez tackle had fallen kindly into his path.
Mandzukic, who shook off an early knock to head over a Koke corner earlier in the first half, pulled one back for last season's runners-up on 38 minutes when he powered Cristian Ansaldi's cross into the net.
