Bristol beat their west country neighbours Gloucester at Kingsholm for the first time since March 1994.
The defeat, the third in a row, leaves the home side possibly without a registered prop for next weekend’s European Shield quarter-final tie at home to Brive.
The victory for Bristol eases their relegation worries as they are now 11 points clear of basement side Leeds Tykes who play Wasps tomorrow, with four matches remaining at home to Newcastle and Northampton and away to Bath and finally Leicester.
The home side were forced to play the final quarter with just 14 men when replacement prop Terry Sigley was shown the red card by referee Wayne Barnes for an alleged stamp on the face of former England hooker Mark Regan, who himself had spent 10 minutes in the sin-bin earlier in the game.
Gloucester made a storming start when James Simpson-Daniel scored the opening try, taking the scoring pass from fellow centre Wayne Allen.
Ludovic Mercier added the extras and, 10 minutes later, a 22-metre penalty from the left of the posts but missed a second from 40 metres out.
As the game went in to the second quarter Bristol came into it game through a penalty from fly-half Jason Strange and Gloucester led 10-3 at the interval although they were struggling to contain the visitors.
Bristol maintained the pressure after the break and were rewarded with a try from England A skipper Shaun Perry in the left corner.
The conversion saw Strange level the scores and then he added a penalty to put the visitors in front for the first time in the game.
When Sigley was sent off it meant the scrums were uncontested but, despite being down to 14 men, Gloucester still managed to gain the advantage as Anthony Allen cut back on a lovely angle to score.
But Bristol still had time to come back as Strange kicked cross field.
The ball bounced between Brian Lima and Gloucester full-back Jon Goodridge.
Lima dribbled the ball, picked up and ran the 30 metres to the line and slid over with a defender failing to stop the try.
Strange added the conversion give Bristol a much deserved victory.