Few expected a young and inconsistent Ulster side to be able to challenge the holders, though the United Rugby Championship side did triumph on their last visit to the Stade Ernest-Wallon in 2022.
However, any optimism was shattered after 90 seconds as Toulouse scored the first of six tries in the opening 40 minutes.
Dupont was at the centre of it all as he sent Santiago Chocobares down the middle before the ball was played wide for Lebel, who produced a superb finish in the corner.
Ntamack was the next to crash over from close range from Dupont’s pass, and it looked like it would be a long afternoon for the visitors.
However Richie Murphy’s young side responded and McCormack dotted down in he 12th minute after Scott Wilson was stopped just short of the line as the miserable drizzle continued to teem down in southern France.
McCormack’s try was brief restbite as Toulouse came again when Meafou stretched out over the line for a third score.
Ntamack thought he had secured the bonus-point midway through the half when he scampered over from a scrum, but it was ruled out for an infringement at the set play.
Ulster had the rare chance to build a platform when Aidan Morgan looked to kick into the corner from a penalty, but he sent the ball straight into the in goal area and play was brought back.
Toulouse showed their clinical edge and punished the error.
From the resulting line out that gave Toulouse possession, the French side worked the ball through the hands for Thomas Ramos and Lebel to race down the line, and the wing popped it inside for Ange Capuozzo for another scintillating score.
A fifth followed almost immediately when Lebel was brought down just short, but Dupont reacted quickest to touch the ball down over the line.
Ulster refused to go away and, after another penalty advantage, Morgan’s pass took three players out of the game and Moore was able to race under the posts.
Toulouse powered over against Meafu crashed over in the final play of the half and the imperious Ramos kicked his fifth conversion.
The pressure continued after the restart and Italy international Capuozzo almost danced over, and a seventh try came when Chocobares rounded off another devastating move that started on the halfway line.
Dupont’s stunning crossfield kick was found Capuozzo with 24 minutes left to play and the talismanic Frenchman was soon withdrawn ahead of their second match in Exeter.
Moments after the ball was held up over the line in Ulster’s first venture into the Toulouse 22, replacement Henderson spotted a gap to squirm over the line.
Ulster had more possession as they pushed for a bonus point score, but a penalty try for Toulouse in the final play added insult to injury, and Murphy’s wounded side will look to respond at home to Bordeaux.
