Manchester City secured a last-16 spot in the Champions League but failed to turn their complete dominance into more than a 1-0 win over Olympiacos.
Eager to put Saturday's 2-0 Premier League loss to Tottenham behind them, Pep Guardiola's side controlled proceedings in Wednesday's Group C clash in Athens.
But they had only one goal to show for it as Phil Foden, who wowed for England during the international break, swept the visitors into a first-half lead that never came under threat from the toothless hosts.
Guardiola, who signed a new contract last week, saw his side frustrated by a combination of profligate finishing and fine goalkeeping from Jose Sa.
City, who scored nine goals across their opening three group games, were quickly on the front foot and Foden stung the palms of Sa with a low drive, with the goalkeeper also gathering a Gabriel Jesus header.
Jesus came far closer to breaking the deadlock on the half-hour mark, racing in behind before seeing his shot blocked away by the defiant Sa.
The opener finally arrived in the 36th minute, Foden converting from Raheem Sterling's back-heeled assist after City's slick play had Olympiacos chasing shadows.
Sterling had the busy Sa scrambling across his line to repel a dipping free-kick in first-half stoppage time, with City denied again after the interval as Ilkay Gundogan's effort flashed wide and Joao Cancelo's flick was saved.
Olympiacos were simply not able to apply any pressure – their first shot did not arrive until the 88th minute – leaving City to coast to a win that was brightened further by the late introduction of Sergio Aguero from the bench after an injury lay-off.
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The loss at Spurs left City with just 12 points from eight matches and in the unfamiliar territory of the Premier League's bottom half.
This result was a tonic to those domestic woes and it affords Guardiola the chance to make some changes for the remaining two group games, knowing safe passage to the knockout phase is assured.
For Olympiacos, while second spot is still up for grabs, a third-place finish and a berth in the Europa League might be a more likely prospect.
Foden shines bright
Foden scored twice for his country in an eye-catching display against Iceland in which he also showcased some dazzling skills.
He was lively in Greece too, keeping his cool to score what proved to be the winner with one of his six shots, while also creating four chances.
Sa under siege
City had 11 shots on target, seven coming during a first half in which the hosts failed to even register a touch in City's penalty area, so Sa was indeed a busy man.
He was an excellent last line of defence but his all-action outing stood in stark contrast to the anonymous performance of the Olympiacos attack.
Konstantinos Fortounis had just 53 touches and not one of them was a shot on target.
City host Burnley this weekend before a trip to Porto next Tuesday, while for Olympiacos it is a top-of-the-table clash at Aris before heading to Marseille on the European stage.