Cricklade overcame a half-time deficit to ease their own Dorset & Wilts One North relegation fears and almost certainly condemn Marlborough to the drop with a 23-7 success.
The home side made an awful start, when poor defending allowed 14-man Marlborough a converted try.
A good break by Mark Adams put Jonathan Crowe into space. After a good sidestep he ran through four players to score a try he converted himself.
Marlborough continued to defend with determination.
Gradually though, Cricklade wore down their opponents and Marlborough coughed up two penalties that Gavin Russ converted to cut the deficit before the break.
The hosts picked up after the interval, but Marlborough spoiled well in defence.
Visiting skipper Geraint Jones made some good breaks and Crowe was well supported by fellow centre Andy Hay and wings Robin Adams and Chris McKenzie.
But they were eventually carved open.
Steve Gee's crossfield run appeared to be leading nowhere, until he suddenly changed direction, found a gap and went all the way to the line.
The try was unconverted but Cricklade's charge was growing.
Marlborough did push forward again, earning good field position from Jones' kick.
And it was not until Gordon Aitken found Simon Tetlow wide on the left that Cricklade were able to score their second, the conversion again awry.
Both sides had opportunities as time went on, but Cricklade had the advantage of the extra man and it was no surprise that as the visitors began to tire.
Aitken was then able to burst through for the final try under the posts, Sam Gay slotting the easy conversion to set the seal on victory.
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