A pair of goals from Gary Hooper in the 0 win over St Mirren on Sunday.
It took just six minutes for Celtic to seize control of the match as a one-two on the edge of the penalty area allowed Anthony Stokes to find Hooper close to goal for an easy finish.
Daniel Majstorovic should have doubled the lead when he missed the target with a close-range header, but a second goal arrived just a few minutes later courtesy of an error in the St Mirren defense.
Paul McGowan's poor pass was intercepted by Hooper and he dribbled in on goal and slotted his shot past goalkeeper Craig Samson.
St Mirren began to get into the game after the poor start, but a few nice saves from Celtic goalkeeper Fraser Forster kept the Saints off the scoreboard.
Celtic has now won four of its first five games to start the season.
Rangers 2, Aberdeen 0
Glasgow, Scotland - Rangers won its fourth straight match on Sunday, defeating Aberdeen, 2-0, at the Ibrox Stadium.
Steven Davis put the hosts in front after 15 minutes and Steven Naismith secured the win with a goal in stoppage time, handing Aberdeen its fourth loss in five games.
Hearts 2, Hibernian 0
Edinburgh, Scotland - Hearts collected three more points on Sunday at Tynecastle Stadium with a 2-0 win over Hibernian that lifts the club into fourth place.
Ryan Stevenson's goal in the 39th minute got the scoring started and Andy Webster doubled the advantage 20 minutes from time, securing a win for Hearts that gives the club seven points from its last three games.
Hibernian, meanwhile, has lost four of its first five games and sits on the bottom of the league.