Harlequins claimed a shock 31-24 victory at four-time champions Toulouse to throw Pool Six of the Heineken Cup wide open.
Mike Brown scored two tries, either side of Joe Gray's first-half effort, while Nick Evans kicked 16 points as Harlequins became the first team to win a European tie at Toulouse in almost three years.
Harlequins led 15-10 at half-time but were forced to survive a second-half onslaught as well as the loss of sin-binned captain Nick Easter for the final 10 minutes.
Despite that, Evans kicked two late penalties after Brown's second try to claim a famous win while Toulouse were left to rue 12 missed points from the boot of Luke McAlister.
Scrum-half Jean-Marc Doussain scored a try among his 15 points though that was not enough for Toulouse, who remain top of Pool Six, but now only a point ahead of Harlequins and four clear of Gloucester.