Reo Hatate set up Celtic's opener, while Daizen Maeda and Kyogo Furuhashi added further goals before halftime to seal a 3-0 victory over visiting Livingston and maintain a nine-point lead atop the Scottish Premiership on Wednesday.
Ange Postecoglou's men went ahead in the 29th minute when Hatate gathered at the left of the area and laid it back for Greg Taylor to fire past Livingston keeper Shamal George.
Maeda doubled the lead four minutes later when he blocked an attempted clearance near the goal mouth, sending the rebound careening into the net.
Furuhashi netted his league-leading 18th goal in first-half time added, controlling a long ball and weaving downfield before steering his shot across a helpless George and into the bottom corner.
The latest addition to the Scottish champions' Japanese contingent, 2022 J-League player of the year Tomoki Iwata, came off the bench in the closing minutes at Celtic Park.
In the Portuguese top flight, Hidemasa Morita scored a brace as Sporting Lisbon thrashed 10-man Braga 5-0.
The Samurai Blue midfielder was quick to react following a corner kick, smashing home the opener from close range in the ninth minute. He made it 2-0 moments before the halftime whistle, firing from the middle of the area as Sporting capitalized on a defensive mix-up.
Braga were reduced to 10 men when defender Sikou Niakate picked up his second yellow card in the 49th minute at Lisbon's Jose Alvalade Stadium.
In France's Ligue 1, Ado Onaiwu struck his first goal of the season for Toulouse in the 88th minute of a 4-1 win over visiting Troyes.