Darren Jackson, the Scottish international signed this summer from Hibernian, netted the home debut goal he wanted just as the Celtic faithful were expressing mild anxiety at the lack of goals.
As in the first leg, Andreas Thom eased initial nerves with a coolly struck penalty, this time after 19 minutes. Richard David had brought down Simon Donnelly for a clear spot-kick.
However, Inter then held firm for a while, and it was only three minutes before the break that Celtic's control of the game was confirmed. Jackson's header was followed moments later by the former Aston Villa man, Tommy Johnson, converting a cross under pressure for the third goal.
After the break, David Hannah capped a fine move with a fourth goal in the 63rd minute. With five minutes remaining, the substitute Chris Hay was on hand for a fifth.
Wim Jansen, Celtic's head coach, said: "There is enough time for us to improve before the next round in Europe, when I know we will be stronger." His two latest recruits - Craig Burley from Chelsea and Henrik Larsson from Feyenoord - were not signed in time to be available last night.
Celtic: Marshall; Boyd, McKinlay, McNamara, Stubbs, Jackson, Thom, Johnson, Donnelly, Hannah, Gray.
Inter Cable-Tel Cardiff: Ellacott; Hewitt, Rickard, David, Philpott, Davies, Warton, Burrows, Haig, Gibson, Williams.
Referee: A Micallef (Malta).Reuse content