Goals in either half from Georgios Samaras and Gary Hooper helped Celtic extend their advantage at the summit of the SPL against bottom side Dundee.
The defeat sees the Dens Park side fall further behind both St Mirren and Ross County, who both picked up vital points earlier in the day.
Dundee made two changes from the side that were thumped at Inverness CT at the weekend, with Stephen O’Donnell and Ryan Conroy taking the places of Iain Davidson and Nicky Reilly, while the visitors only made one change, with Tony Watt coming in for Lassad Nouioui in attack.
The first chance of the game came for Barry Smith’s side, after a poor pass out of defence by Emilio Izaguirre saw Victor Wanyama dispossessed by O’Donnell, but the midfielder’s strike went just over Fraser Forster’s bar.
Celtic then smacked the bar when Efe Ambrose got his midriff onto a corner from the left by Charlie Mulgrew after Dundee stopper Rab Douglas had scrambled a strike from Watt out of play.
Neil Lennon’s side finally opened the scoring when Douglas could only parry out a Watt strike from another Mulgrew corner into the path of Samaras and the Greek striker, facing away from goal hit an overhead kick into the roof of the Dundee net.
Samaras should have doubled the lead as he broke from his own half, playing the ball to Beram Kayal, before taking the return pass from the Israeli midfielder and racing into the box, but managed to tip his strike round the post.
The visitors were lucky not to be a man down just before the break, as Kelvin Wilson appeared to strike out a John Baird after the Dundee forward had been tangling with the English defender, but luckily for Celtic referee Iain Brines failed to see the incident.
Within five minutes of the second half Dundee should have got level as Conroy raced down the left wing, beating Scott Brown, before crossing onto the head of Colin Nish, but unfortunately for the on-loan striker, Forster made a world-class save to deny him and keep Celtic ahead.
Celtic were getting pinned back in their own half by the relegation contenders, but when they did manage to push forward they found former Celt Douglas in form as he managed to save well after a cross from substitute Mikael Lustig was diverted to his own goal by Kyle Benedictus.
The visitors doubled their advantage when Hooper broke the Dundee offside trap to get on the end of a long ball from Lustig and the English striker lobbed the ball over Douglas to put Celtic in a commanding position.
The league leaders continued to press forward for the remainder of the game, but they couldn’t find a way past Douglas in order to extend their lead as they increased the gap on both Inverness CT and Motherwell at the top of the league to seven points.