Toulon's unbeaten home record in the European Champions Cup came to an abrupt halt on Saturday as Saracens produced a stunning victory in the opening game of Pool 3.
Sean Maitland, Richard Wigglesworth and Chris Wyles all scored tries as the Premiership champions ran out 31-23 winners against the three-time tournament winners at Stade Felix Mayol.
The visitors' turned on the style in the first half as they established a 25-6 lead and although the French side replied through tries from prop Levan Chilachava and wing Bryan Habana they held on.
Owen Farrell – on his first competitive appearance of the season – was vital for Sarries as he kicked 16 points to give Mark McCall's side a surprise victory on French soil.
To compound a day to forget for the hosts, they also lost wing Josua Tuisova to a suspected broken ankle.
Scarlets were the other side to open their Pool 3 campaign with a victory, ending a run of eight consecutive defeats in Europe by beating Sale 28-11.
Canadian wing DTH van der Merwe scored two of the home side's three tries at Parc y Scarlets, while the visitors lost Ross Harrison and Andrei Ostrikov to yellow cards in the second half.
In Pool 2, full-back Rob Miller and scrum-half Joe Simpson shared four of Wasps' 12 tries in a crushing 82-14 win over Zebre at the Ricoh Arena.
But the pool's other game was an altogether tighter affair, with Toulouse continuing their recent poor away form in the competition by losing 23-21 to Connacht
The Irish province trailed by 10 points at the break, but fought back in the second half and Bundee Aki's 64th-minute try proved enough to secure a famous win for Pat Lam's men.
Leinster also enjoyed a home victory over French opposition, downing Castres 33-15 in their Pool 4 clash.
Hooker Sean Cronin grabbed two of his side's five tries, with fellow-front-rower Jack McGrath also finding the line.
Stephen Myler, meanwhile, was Northampton's hero as he landed an 80th-minute penalty to secure a 16-14 win over last season's Challenge Cup winners, Montpellier.
The hosts shrugged off their indifferent domestic form to take an early lead through flanker Calum Clark's try and although Frans Steyn replied in kind for the French side just before the break, Myler's four successful kicks ultimately proved decisive.