Liedson scored twice for the home side with Diogo Solomao, Nuno Maniche and Helder Postiga also finding the target in a match which saw chance after chance for both teams.
Stef Wils grabbed Gent's consolation, but the team prop up the standings with just a single point.
Sporting came into the match on the back of two wins in the pool, and took just seven minutes to take the lead against the Belgian visitors.
Pereira curled in a cross from the right wing which Solomao smashed into the bottom-left corner from 12 yards out.
Just six minutes later and the Portuguese hosts had doubled their advantage thanks to the boot of Liedson, who hit a shot from 25 yards which flew beyond Gent keeper Bojan Jorgacevic into the bottom-right corner.
Gent's response to the double blow was admirable and four minutes later they pulled a goal back thanks to Wils, who held off the home defence to fire in from the centre of the area.
But their jubilation was short-lived as Pereira curled in another pin-point cross after 27 minutes which was stabbed in by Liedson.
The chances continued to come at both ends and Jorgacevic made a good save to deny Maniche after 36 minutes.
But two minutes later the midfielder came good with Sporting's fourth, tapping home Pereira's cross from close range.
Gent pressed hard towards the end of the half in a bid to reduce the gap once more, but Ibrahima Conte could only power his effort from distance over the bar.
Sporting's dominance in front of goal continued after the interval with Postiga making it 5-1 after 60 minutes, turning in Solomao's cross from the edge of the area.
Liedson could have completed a hat-trick six minutes later with a header which fell inches wide of the mark.
And Jorgacevic pulled off a good save from Pereira's strike five minutes from time to deny Sporting once more, although the damage had already been done.