Reo Hatate secured Celtic a narrow 1-0 victory over second-placed Aberdeen, sending them seven points clear at the top of the Scottish Premiership table.
The Japanese international struck in the 78th minute, meeting Greg Taylor's pass over the top to rifle the winner into the bottom corner.
In a tight first half, Duk was denied by Kasper Schmeichel before Alistair Johnson's header was turned narrowly past the post by Jamie McGrath.
Paulo Bernardo thought he had given Celtic the lead when he scored directly from a corner, though the goal was ruled out due to a foul on Ross Doohan.
Ester Sokler had the opportunity to equalise late on, only for Cameron Carter-Vickers to turn his effort over the bar as Celtic kept an 11th clean sheet of the season.
A big three points on the road! #ABECEL | #CelticFC pic.twitter.com/JauCHpa6b3
— Celtic Football Club (@CelticFC) December 4, 2024
Meanwhile, Rangers continued their recent run of fine form with a 6-0 thrashing of Kilmarnock.
It was their second win by that scoreline this season, having also beaten Ross County on matchday three, with James Tavernier opening the scoring in the 37th minute with his first goal of the campaign.
Philippe Clement's side turned up the heat after the break, with two goals in two minutes from Danilo and Hamza Igamane putting them 3-0 up.
Vaclav Cerny then drove a reverse shot into the back of the net shortly after the hour mark before substitute Cyriel Dessers scored two first-time goals to move Rangers just four points behind Aberdeen with a game in hand.