Leroy Houston scored a double as Bath downed London Welsh 29-14 in atrocious conditions to officially condemn the Exiles to relegation.
Bath quickly opened up a lead with early tries for Rob Webber and Houston, but London Welsh responded with a converted score from Nic Reynolds.
And Bath proved too strong in the second half, adding three more tries through Sam Burgess, Houston and Alafoti Faosiliva to secure maximum points.
Welsh needed a bonus-point win if they were to keep their mathematical hopes of survival alive, but it looks ever more likely that they will finish the season without a win.
Welsh had conceded an average of 52 points in their last four matches, while Bath were looking to build on their 12-3 win over Sale on their last outing.
Two tries in the first 25 minutes of the match laid an excellent platform for the visitors. Webber touched down following a well-executed catch and drive, but the strong wind at the Kassam Stadium prevented Tom Homer from adding the extras.
Bath doubled their lead on 21 minutes when Houston capitalised on confusion following a line-out to ghost over on the left. Homer was again wide with the conversion, but Bath held a ten-point cushion.
Welsh found a quick response to the second concession, however, and they were back in the game when Reynolds went over for Tristan Roberts to convert.
The score narrowed Bath's lead to just three points, despite a dominant performance from the visitors. But Bath scored the crucial first try of the second half to re-establish a buffer.
It came from Burgess, after Bath had managed to steal the ball at a Welsh lineout. And this time there was no quick response from Welsh, as Bath took a stranglehold on the contest through two more quick scores.
Houston grabbed his second try with a simple pick up and drive from the scrum, before Faosiliva secured the bonus point for the visitors. Homer converted Faosiliva's try to make the score 7-29 with little over ten minutes remaining.
But Welsh scored the final try of the afternoon through Opeti Fonua, who was driven over by his team-mates. Will Robinson converted to give the Exiles the final word.
For London Welsh:
Tries: Reynolds, Fonua
Cons: Roberts, Robinson
Yellow Cards: Trevett, Schofield
Tries: Webber, Houston 2, Burgess, Faosiliva
Cons: Homer 2
London Welsh: 15 Seb Jewell, 14 Seb Stegmann, 13 Nic Reynolds, 12 Tom May (c), 11 Alan Awcock, 10 Tristan Roberts, 9 Rob Lewis, 8 Opeti Fonua, 7 Carl Kirwan, 6 Lachlan McCaffrey, 5 James Down, 4 Dean Schofield, 3 Ben Cooper, 2 Koree Britton, 1 Nathan Trevett.
Replacements: 16 Nathan Morris, 17 Eddie Aholelei, 18. Jack Gilding, 19 Ben West, 20 Richard Thorpe, 21. Paul Rowley, 22 Will Robinson, 23. James Lewis.16 Nathan Morris, 17 Eddie Aholelei, 18. Jack Gilding, 19 Ben West, 20 Richard Thorpe, 21. Paul Rowley, 22 Will Robinson, 23. James Lewis.
Bath: 15 Tom Homer, 14 Semesa Rokoduguni, 13 Sam Burgess, 12 Kyle Eastmond, 11 Olly Woodburn, 10 Ollie Devoto, 9 Micky Young, 8 Leroy Houston, 7 Alafoti Faosiliva, 6 Carl Fearns, 5 Dominic Day, 4 Stuart Hooper (c), 3 Kane Palma-Newport, 2 Rob Webber, 1 Nick Auterac.
Replacements: 16 Ross Batty, 17 Beno Obano, 18 Max Lahiff, 19 Matt Garvey, 20 David Sisi, 21 Chris Cook, 22 Matt Banahan, 23 Horacio Agulla.
Venue: Kassam Stadium, Oxford
Referee: Thomas Foley
Assistant Referees: Peter Huckle, Paul Burton
TMO: David Sainsbury