Celtic recovered from their European setback with a Scottish Premiership victory over St Johnstone here that should have been more comprehensive.
Neil Lennon's side played well only to lose 2-0 to Milan in their Champions' League Group H opener in the San Siro on Wednesday and they responded yesterday with a first-half onslaught against their visitors.
Teemu Pukki, the Finnish striker who was making his first start for his new club, opened the scoring with a drive in the 10th minute.
Charlie Mulgrew added a second with a fine left-footed shot 16 minutes later and Celtic looked on track to rack up a high score.
But the second half turned into something of a non-event for the Scottish champions, who were given a scare when Liam Caddis, a St Johnstone substitute in place of David Wotherspoon, bundled in from Dave MacKay's cross with nine minutes remaining.
Another St Johnstone replacement, Stevie May, almost made Celtic pay for their failure to make the game safe in the first half, but his instinctive effort struck the post in added time.
Fraser Forster, Celtic's goalkeeper, was also required to make a superb late save to deny McKay.
The result moves Celtic level on points with Inverness Caledonian Thistle at the top of the SPL table after the in-form Highlands side suffered their first defeat of the season at Aberdeen.
Scott Vernon's 81st-minute strike proved decisive in a 1-0 win for Derek McInnes' side, who are now only three points behind the leaders in third place.
Celtic (4-4-2): Forster; Matthews (Biton, 46), Ambrose, Van Dijk, Izaguirre; Commons (Samaras, 59), Brown, Mulgrew, Boerrigter; Stokes, Pukki (Balde, 87).
St Johnstone (4-1-4-1): Mannus; Mackay, Wright, Anderson, B Easton; Cregg (Hasselbaink, 87); Millar, Davidson (May, 61), McDonald, Wotherspoon (Caddis, 68), MacLean.
Referee Alan Muir.