Olympiacos - Athletico 3-2

The Greek champions were arguably second best for long periods of the Group A clash at the Karaiskakis Stadium, but were rewarded for their clinical finishing.

Atleti will rue their profligacy in front of goal and coach Diego Simeone - who took a watching brief from the stands due to a touchline ban - must wonder how his side failed to take at least a point back to the Spanish capital.

The La Liga champions came agonisingly close to winning the Champions League in last season's final, as they held a 1-0 lead until the 93rd minute before going on to lose 4-1 to city rivals Real Madrid after extra time.

That European campaign saw Atletico go unbeaten in six away contests, but the visitors were two goals adrift by the 31st minute following Arthur Masuaku's driven effort, then on-loan Barcelona forward Ibrahim Afellay added a second with a composed finish.

Mario Mandzukic reduced the deficit before half-time, but Kostas Mitroglou, who returned to the club in the last transfer window after a short and unsuccessful spell at Fulham, slid home from close range to make it 3-1.

Griezmann offered hope of a late fightback when he tapped home Koke's fizzed cross in the 86th minute, but in the end Olympiakos took home the three points.