Rugby fell to a second successive league defeat - this time at the hands of their local rivals on a disappointing evening for Town at the Dunley Way.
Kurtis Revan came into the starting line-up in the absence of the injured Danico Johnson, and on a drizzly, murky evening, Rugby had the first real chance of the game in the 14th minute, when Revan drove into the left hand side of the penalty area, however his effort was wide and high over the bar.
The home side produced some decent one touch football halfway through the half, although forward Tendai Daire's final shot was ultimately an easy one for Sam Lomax.
Lutterworth took the lead in the 33rd minute when Marshal Keenan found the ball in the box and passed coolly to Daire who blazed a low shot past a stranded Lomax.
Valley nearly equalised just before half time when a good cut-back across goal by Caine Elliott to Dylan Parker saw his shot saved on the line by Kade Lewis.
Rugby started the second half the brighter side and were soon back into the game in the 49th minute through Revan, when the striker crisply fired home a first-time effort to Ryan Seal's quickly taken corner.
Town were now on the front foot, with both Loyiso Recci and Lee Thomas then having decent efforts on target. Lomax made an impressive double save midway through the half with the follow-up effort to the second stop blocked on the line by a Town defender, as the home side's hopes of a goal were thwarted in a crowded penalty area.
Rugby had a number of chances to win the game too though, with Seal missing out from close range representing the best of that bunch, but the sucker punch came in the 85th minute when Abdul Rahman Sunmonu got the winner for Lutterworth with a low shot from close quarters after Callum Riley's cross had split the Rugby defence.
The visitors nearly scored a last gasp equaliser when after keeper Lomax had ventured forward for a late corner, his head on was poked towards the goal but the match officials did not agree with the appeals from Valley players and fans that the ball had crossed the line before a Lutterworth boot cleared it.
Line-up: Lomax; Rosser, L Thomas, Recci, Francis; Hancocks, Elliott; Revan (C Thomas), Evans, Seal; Parker. Subs not used: Marsden. Booked: None.