It was a must-win game for the Yorkshiremen and an 13-6 interval lead encouraged hopes of only a second win of the season to keep alive their hopes of survival.
Bristol had other ideas, however, and after Leeds wing John Holtby was sinbinned in the 50th minute, they ran in three tries during a devastating purple patch.
Scrum-half Shaun Perry was the prime beneficiary, touching down in the 51st and 57th minutes before centre Rob Higgitt added a third on the hour mark.
The hat-trick of tries put Bristol in total control and skipper Joe El Abd added a late fourth to secured his side a bonus point.
It was Bristol's first away win in the league since January 2007 and condemned Leeds to their 14th defeat from 15 Premiership outings this season.
Stuart Lancaster's men are rock-bottom of the table with a pitiful tally of six points and not even their most ardent follower would back them to survive now.
And yet their customary spirit has never wavered, despite being outplayed and outclassed on such a regular basis.
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