Charlie Mulgrew made sure Celtic showed few ill effects from their midweek Champions League defeat in Milan as they drew level at the top of the Scottish Premiership with a 2-1 win over St Johnstone.
Mulgrew blasted home from 25 yards in the 26th minute to cap a fine reaction from Neil Lennon's men, who had needed just 11 minutes to grab the lead when Teemu Pukki slotted home after fine work from Anthony Stokes.
The home side looked set to go on to claim a lopsided win but the visitors showed admirable resolve and dug in, with Liam Caddis making for some anxious final moments after reducing the deficit nine minutes from time.
Celtic now sit behind leaders Inverness Caledonian Thistle on goal difference with a game in hand after Terry Butcher's men suffered their first defeat of the season, 1-0 at Aberdeen.
The Dons dominated the opening period and the visitors had goalkeeper Dean Brill to thank for keeping them level after pulling off superb saves to deny Ross Draper and Cammy Smith.
But Aberdeen grabbed their winner in the 81st minute when substitute Scott Vernon, who had only been on the pitch for three minutes, fired a volley on the turn which beat Brill and sealed the points.