St Mirren were beaten by Celtic on matchday three in the William Hill Premiership.
An early Callum McGregor goal was added to by a Reo Hatate strike a few minutes before half-time. Alistair Johnston added a third for the visitors with just over 20 minutes remaining to consign Saints to defeat.
New signing Killian Phillips made his debut from the start after joining from Crystal Palace earlier this week. Manager Stephen Robinson was also able to bring captain Mark O'Hara back into the starting eleven after injury. Those were among five changes for Saints with Richard Taylor, Jonah Ayunga and Jaden Brown also coming in for Scott Tanser, Roland Idowu, Oisin Smyth, Fraser Taylor and Mikael Mandron.
The visitors struck first with the opening attack. There were just three minutes on the clock when McGregor scored from distance. The Celtic captain rifled a low strike into the bottom right hand corner from 20 yards leaving Ellery Balcombe with no chance.
The Saints' goalkeeper was called into action a little less than 10 minutes later when he made an impressive double save from Hatate and Adam Idah. The stopper denied Idah again on 22 minutes when the forward had found himself in on goal, but Balcombe stuck a foot out to block.
Celtic would add a second on 33 minutes when Hatate doubled the visitors' advantage. Johnston's switch met the head of Daizen Maeda who had got ahead of Shaun Rooney. The Japanese forward nodded down into the path of countryman Hatate who lashed into the net via the far post.
Buddies boss Stephen Robinson made two changes at the break with Idowu and Mandron introduced in place of Alex Gogic, who picked up an early first-half booking, and Ayunga.
Saints would have their first real attempt at goal 10 minutes after the restart when Jaden Brown let fly from distance, but his strike was straight into the arms of Celtic goalkeeper Kasper Schmeichel.
Balcombe was alert to substitute Kyogo Furuhashi's danger when the striker got in on goal with the goalkeeper was out quickly to turn the first time effort over. But Celtic would add a third on 71 minutes. Substitute Nicholas Kühn worked his way in from the right and picked out Johnston who had time to switch the ball onto his right foot before thumping high into the net.
Full-Time: St Mirren 0-3 Celtic
St Mirren: Balcombe, Fraser, Iacovitti, R.Taylor, Rooney, Phillips (Smyth 74), Gogic (Idowu 46), O'Hara (c), Brown, Ayunga (Mandron 46), Olusanya (Sutherland 87)
Subs Not Used: Urminsky, Kenny, Bwomono, Tanser, F.Taylor
Celtic: Schmeichel, A.Johnston, Carter-Vickers, Scales, Taylor (Ralston 75), McGregor (c), Hatate (Turley 89), Bernardo (Holm 75), Forrest (Kühn 60), Maeda, Idah (Furuhashi 59)
Subs Not Used: Sinisalo, Welsh, Palma, Yang
Referee: Chris Graham
Assistant Referee: Calum Spence
Assistant Referee: Colin Drummond
Fourth Official: Gavin Duncan
VAR: Steven McLean
Attendance: 6,948
