Victory for 11th-placed Sale Sharks at home against Gloucester would potentially leave the Exiles needing to avoid defeat when Northampton visit the Kassam Stadium, or face finishing last and meaning likely demotion.
Skipper Jonathan Mills said: "We've got three cup finals between now and the end of the season, and it starts on Sunday against Northampton. We are fighting for our livelihoods and to keep the club in the Premiership. We are certainly not giving up."
He added: "Obviously, the ball is in Sale's court, but we've got to take care of our own side of things. Fair play to Sale, they've picked their season up, but we are still fighting.
"It's not about where you are now in the table, it's about where you are after 22 games. We have got three games left and we will be giving everything to win them all.
"Although we have been struggling for wins recently, we've been playing some of our best rugby of the season and we still believe we can do it."
Sale show just one switch from the side that drew against London Irish last time out - wing Will Addison replaces Charlie Amesbury - as they look to put further distance between themselves and Welsh.
Gloucester, though, are pushing hard for a play-off place, with just two points currently separating themselves in fifth and third-placed Harlequins as the battle intensifies for semi-final berths alongside likely qualifiers Saracens and Leicester.
"The table is so congested that fourth spot could go to anyone at the minute," said England wing Charlie Sharples, who is on the Gloucester bench at Salford City Stadium. "We have three games left, two of which are tough away games, but we have every chance of making it.
"We have to look at it as knockout rugby now. We are desperate to get into that top four. If we lose points now, someone else will take them and move ahead."
- Sports & Recreation