Town's stuttering form of late continued at Butlin Road, when they dropped more points against mid-table Peterborough Northern Star.
The lively-looking Peterborough visitors had established a two goal lead before recent striker signing Edwin Ahenkorah's late brace at least ensured Valley salvaged a draw from the affair.
Rugby boss Carl Adams handed returning keeper Louis Connor a start between the sticks, with Fazel Koriya and Simeon Tulloch also back in from the off in place of Justin Marsden and Josh Steele.
The game started slowly, and it was the away side that registered its first shot when Sam Wilson curled one wide from distance.
Charlie Evans did send the ball onto the back stanchion in a rare attacking highlight for Town, with the hosts' only other significant threat of the opening half an hour coming when Richard Blythe surged into the Star box - only to fail to fashion a telling strike.
Jack Bloodworth had tested Connor with a long-range free-kick and Matthew Barber had seen his decent effort blocked, ahead of the game's first goal which came when Harry Fitzjohn looped his header over Connor after Bloodworth had picked him out with his floated set-piece.
Lewis Rankin finally called Peterborough keeper Connor Barker into action with a low take, before the visitors could easily have doubled their advantage when Connor's legs kept out Jake Sansby's shot.
Ahenkorah found the side netting and a Liam Francis header lacked power and precision as the first half drew to a close, but generally it was another unconvincing opening 45 minutes from Rugby.
When Bloodworth struck a great free-kick beyond the reach of Connor from thirty yards three minutes after the restart, it appeared the scene was set for Valley's second home league defeat of the season - with Wilson then almost adding a third with an acrobatic attempt that drifted just wide.
Rugby's most likely route back into the game always seemed to be from a set play, with Loyiso Recci drawing a good save to his header from Rankin's corner and both Francis and Recci denied from a further one by Koriya.
It indeed was a corner - this time by Evans - that generated Town's first goal, with Ahenkorah claiming the decisive contact after a goalmouth scramble had ensued on 72 minutes.
Francis then had a shot blocked and Keenah Rosser headed over, as Rugby pushed forward in numbers in search of an equaliser - which eventually came in stoppage time when Ahenkorah smartly volleyed home Koriya's lay-back, after Dom Perkins had chipped the ball into the penalty area.
Line-up: Connor; Rosser, Koriya, Recci, Francis; Perkins, Blythe (Holloway); Rankin, Tulloch (Marsden), Evans; Ahenkorah. Subs not used: Hill, Kavanagh, Steele. Booked: Perkins, Recci.
Peterborough line-up: Barker, Panting, Strachan, Dunn, Cox, Bloodworth, Sansby, Wilson, Hill-Seekings, Fitzjohn, Barber. Subs: Rosser, Blanchard, Rodden.