Celtic moved level on points with league leaders Inverness as they survived a nervy ending to their match against St Johnstone.
Neil Lennon's side dominated the first half entirely and were two goals ahead thanks to a Teemu Pukki shot and Charlie Mulgrew's low drive.
St Johnstone improved after the break and Liam Caddis pulled a goal back with nine minutes remaining.
And Fraser Forster made a great late save to deny Saints' Dave Mackay.
Celtic started with nine of the players who started at the San Siro in their 2-0 Champions League defeat by AC Milan.
Perhaps it was with that match in mind that St Johnstone took to the field resplendent in their AC Milan-style red and black change kit.
Lennon has made public his desire for his players to pick up maximum points in domestic league games after matches in Europe and there was little sign of any early Champions League hangover.
Pukki opened the scoring in his first start, the Finnish striker firing a shot through the legs of St Johnstone keeper Alan Mannus.
The Northern Irish goalie did well to parry Adam Matthews's powerful shot after he broke into the St Johnstone box.
In the 26th minute Celtic doubled their lead. Mulgrew picked the ball up 25 yards from goal and lashed an unstoppable drive low into the bottom corner of the net.
Soon after Mulgrew almost got a second but his curling effort went wide.
St Johnstone's only chance of the first half came from a back-pass header from Celtic left winger Derk Boerrigter which almost caught Forster out.
Boerrigter should have scored minutes later but his header from Anthony Stokes's perfect cross failed to hit the target.
The second half started with Celtic again on the attack, with Stokes hitting a shot just wide of the post.
After showing nothing in the first half St Johnstone became a little more enterprising and substitute Stevie May flashed a header over and midfielder Chris Millar forced a save from Forster.
But it would get better for Saints when substitute Caddis got on the end of a cross and Forster could not keep the ball from crossing the line.
And the visitors thought they might have had a penalty near the end when Steven MacLean went down in the box under a challenge from Stokes but the referee waved play-on.
Saints upped the pressure and a late strike from Mackay forced a save from Forster in injury time after May's flick had struck the post as Celtic endured some nervous closing moments.