Valley suffered yet another single goal margin defeat at Butlin Road last Saturday after a horrendous start to the game which saw them two down within the opening seven minutes.
Levi Rowley pulled one back from the penalty spot for the hosts ahead of the half-time break, but Town could not find a way through again before the end, as their relegation fears deepened.
Gary Moran made three changes to the starting line-up from the previous weekend's home reverse to Loughborough by recalling himself and Trey Brathwaite to the full-back berths, and there was also a place from the off for Aaron Moses-Garvey after the midfielder had served his three match suspension.
Rugby could even have been behind in the opening seconds, but keeper Louis Connor was alert to the danger by smothering out Sam Grouse.
However the game was just four minutes old when the diminutive Reece Morris netted Matt Melbourne's cross from the left.
Connor again quickly advanced from his line to save a further effort from Grouse after the striker had snuck in behind Town's defence, but there was soon a further blow for Moran's men when ex-Rugby man Tom Manship's low free-kick took a decisive touch off Melbourne before squirming under Connor for the visitors' second.
A shell shocked Valley finally gained some kind of foothold on the game, with Kyle Rowley's header towards goal cleared away by a Gresley boot and David Kolodynski having a goal disallowed when he was contentiously adjudged to have been in an offside position.
Ryan Quinn also struck the base of the post with a swinging free-kick, whilst Mitchell Thomson could have done better with his shot from a decent position after Kolodynski had created the chance down the right hand channel.
Town's luck was in though when Moses-Garvey's volley from the edge of the box struck the midriff of Melbourne near the penalty spot, but referee Simon Brown ruled there was also punishable contact with a hand to give Levi Rowley the chance to stroke home from twelve yards.
The chances continued to come for Rugby, with another teasing Quinn free-kick just tipped away by Gresley keeper James Flinder and Levi Rowley driving one just over the bar from twenty yards.
However there was then a major let-off for Town at the other end when Brathwaite's clumsy challenge on Leandro Browne generated the game's second penalty, but fortunately Manship blazed his spot-kick off the top of the bar.
Flinder saved well from Quinn and Moses-Garvey speared one just wide of the target in the closing few minutes of the first half, as the home side looked to capitalise on their good fortune.
The second period was generally a less eventful affair, although the Moatmen almost made another great start when Morris weaved through the Town defence before shooting wide.
Mason Rowley headed one straight at Flinder, before the keeper pulled out another decent save to keep out a rising strike from Quinn, but despite plenty of possession and a series of corners and crosses into the box, the hosts had little to show for their efforts as the half progressed.
In fact it was the visitors that went closest to adding to the game's goal tally, with Connor turning another Morris effort round the post, before later doing the same to a powerful shot by Melbourne.
Substitute Tevin Shakespeare's speculative effort from distance which flew well wide was a rare late opportunity for Town.
Line-up: Connor; Moran (Print), Brathwaite, M Rowley, K Rowley; L Rowley, Moses-Garvey, Thomson (Shakespeare), Quinn (Parsons); Kolodynski, Sterling. Subs not used: Fura, Punter. Booked: Thomson, K Rowley.