Oxford Harlequins had a day to forget in South West 1 with a 30-7 defeat at Old Patesians, so are not mathematically safe.
But Coney Hill, the only bottom-three side who can match Quins' 18 points, also trail by 180 on points difference.
Quins can dispel any doubts by beating Coney at home on April 12.
Patesians made better use of the miserable wet and windy conditions, which scuppered the visitors' running game.
The hosts took the lead with a ninth-minute penalty from full back Rob Trott.
Although Quins half backs Anthony Cope and Frank Jones found some gaps, they fell further behind when flanker Matt Hundle was driven over on 25 minutes.
Centres Beau Wilson and Tom Johnson went close for Quins, who were stung in the final five minutes of the half.
Trott converted a penalty try then scored one of his own to make it 20-0 at the break.
Quins had much of the second half, but wrong decisions cost them points.
Patesians flanker Giles Potter was driven over on 70 minutes and some slack defence allowed wing Matt Norman in late on.
In between prop Paul DeLange forced his way over for Quins' solitary try, converted by Jones.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article