Jonny May scored twice to help Gloucester secure their place in the Heineken Cup next season as they upset leaders Saracens with a 28-23 victory at Kingholm.
The England hopeful crossed twice in the first half while England No.8 Ben Morgan, who recently returned to action following an ankle ligament injury suffered during England's opening Six Nations game against Scotland this season, struck midway through the second-half.
Saracens, meanwhile, remain top of the Premiership, their losing bonus point keeping them four clear of Leicester after centre Joel Tomkins scored two tries, while Owen Farrell converted both scores and landed three penalties.
Saracens were already safely through to the play-offs with a home draw, although they will be disappointed not to go into next weekend's Heineken Cup semi-final showdown against Toulon at Twickenham with a win. Gloucester remain hovering on the play-off zone, lying fifth, yet they still require other results to work for them as the regular domestic season approaches its climax in a fortnight's time.
Gloucester showed a handful of changes from the side dismantled by Sale Sharks eight days ago, including starts for young front-row prospects Koree Britton and Shaun Knight, while Hartpury College product Tom Savage captained the team. Saracens rested England backs Chris Ashton and Brad Barritt, but they were still able to parade a galaxy of international talent in pursuit of a 17th league victory this season.
But Gloucester made all the early running, going ahead through a fourth-minute Freddie Burns penalty before they carved out an impressive try scored by May, who cut inside Saracens fullback Alex Goode's weak challenge.
May, considered a possible selection bolter for this summer's British and Irish Lions tour to Australia, could not have wished for a better start with Lions assistant coach Rob Howley watching from Kingsholm's packed stands. Farrell opened Saracens' account with a 35-metre penalty, and that was the cue for them to awake from their slumber as 10 points in five minutes saw them cruise ahead.
Tomkins finished superbly for a 21st-minute try, gathering the ball one-handed and throwing Gloucester's defence an exquisite dummy before touching down. Farrell converted and then added a penalty, underlining Saracens' ability to keep the scoreboard moving, but Gloucester were in no mood to take a back seat and they hit back spectacularly.
May swooped for his second try, touching down after he collected Burns' kick into space, and the fly-half converted before kicking a penalty that gave Gloucester an 18-13 interval advantage.
Gloucester dominated territory during the second-half's early stages, but they were unable to increase their lead in a game played at an unrelenting pace by backs and forwards. Farrell cut the deficit to two points with an angled penalty midway through the second period, setting up an intriguing final quarter that Gloucester launched in scintillating fashion.
Morgan grabbed lock Lua Lokotui's pass from a restart, and then showed a blistering turning of speed by shredding Saracens' defence through an angled run that saw him touch down at the posts. Burns converted as Gloucester became only the second team this season after Leicester to score three tries in one Premiership game against Saracens, but the visitors immediately enjoyed a temporary one-man advantage when Gloucester scrum-half Dan Robson was sin-binned by referee J P Doyle for a professional foul.
Saracens then cut the gap with Robson still off the field, with Tomkins claiming his second touchdown and Farrell converting, making it 25-23 with nine minutes left. It was a typically resilient effort by the visitors, who pushed hard for a winning score as the clock ticked down, but Gloucester did just enough to stay ahead and sign off at Kingsholm this term with a deserved triumph that was sealed by Burns injury time penalty.