The chat before the game was whether Hibs and their fans could contemplate a victory that might help city rivals Hearts to their first league title since 1960.
It could explain the empty seats dotted around Easter Road for what was a vital game for their own chances of European qualification.
The lack of atmosphere may have contributed to the home side's lacklustre start, but they also looked uncertain at the back in the absence through suspension of goalkeeper Raphael Sallinger and wing-back Felix Passlack from last week's derby defeat, along with centre-half Grant Hanley from the previous week's red card.
McGrath's moment of madness added to their woes, but even by then Celtic were on their way to an 85% domination of possession by half-time.
Defeat was probably no surprise considering Hibs have now failed to win any, and have lost nine, of the 13 league games when they have conceded the opening goal this season.
Since Hibs shocked Celtic 2-1 in Glasgow in February, David Gray's side have won just once in seven outings, losing their latest three, while Martin O'Neill's side have lost only once, winning nine of their 10 games, including their latest five.
Celtic's scorers were probably no surprise either, Maeda having rediscovered his scoring touch and now found the net on his latest three visits to Easter Road.
Iheanacho proved to be the super sub again, just as he had with his extra-time double in the Scottish Cup semi-final against St Mirren, as his fourth goal in five games perhaps handed Celtic the momentum in a seesaw, three-team title race.
Winning is everything at this stage of the season.