Valley were held to a disappointing draw at mid-table Sleaford Town.
Simeon Tulloch's 32nd minute strike had given the visitors a half-time lead after a scrappy opening period.
However despite an improved performance after the break from Carl Adams's men, Sleaford sub Ryan Oliver's equaliser applied another hammer blow to Town's title hopes.
Adams made two changes to his starting line-up, with Louis Connor in for Matt Hill between the sticks and Daniel Kavanagh handed only a sixth league start of the campaign at left-back.
Town carved out the first chance of the game early on, when Edwin Ahenkorah laid the ball off to Charlie Evans - whose effort from twenty five yards failed to trouble home keeper Regan Start.
Liam Hargrave's long range half-volley then flashed wide of Connor's post, with George Couzens doing likewise in rare moments of threat from the hosts.
Evans put in another off-target effort after neat work from Justin Marsden and Ahenkorah, as Rugby eventually began to take control of possession and territory.
Tulloch's opener came after Dan Summerfield had looped one into the penalty area which Start failed to deal with, and after the ball had bounced fortuitously off the Rugby man's back, he did well to hook it into the bottom corner.
It really should have been two-nil before the break, after Valley missed a trio of golden opportunities from the same attacking phase of play.
First Eli Bako's toe-poked shot at the back post was parried by Start and then Liam Francis slipped as he look to set to capitalise on the loose ball. After a further scramble in the box, Marsden finally lifted his effort over the bar.
Town continued on the front foot from the restart, and Evans's shot on the turn came back off the upright after Marsden had played him in.
Marsden was soon playing the role of provider again - this time to Bako, but Rugby's recent signing was denied by a decent one-handed save from Start.
Francis then headed a Marsden centre straight at Start, with Bako also volleying over from a good position.
A rising strike from Summerfield always looked likely to be heading over, as the visitors continued to press for a second goal, before the home side fashioned a leveller out of the blue when Oliver ran onto Tom Siddons's flick to fire home into the bottom corner.
Rugby missed out on the chance of an immediate response though, when Evans could only make minimal contact to Ahenkorah's incisive pass - allowing a Sleaford defender the opportunity to clear.
Further chances followed for Valley, with Loyiso Recci's strong header dealt with by Start, and Lewis Rankin having a shot blocked.
Scott Coupland's looping header - which Bako kept out on the line - was the closest Sleaford came to grabbing an unlikely winner in the final stages, whilst both Summerfield and Evans tried their luck unsuccessfully with late headers.
Line-up: Connor; Rosser, Kavanagh, Recci, Francis; Bako, Summerfield, Marsden; Tulloch (Rankin), Evans, Ahenkorah. Subs not used: Hill, Holloway, Steele. Booked: None.
Sleaford line-up: Start, Worthington, Greenwood, Machin, Newman, Hargrave, Hockin, Armstrong, Siddons, Couzens, Coupland. Subs: Smith, Oliver, Shaw.