With any remaining fears of slipping into League One banished from Loftus Road at the weekend, the threat of relegation looms large for Malky Mackay's Watford side, who have now failed to find a win in their last 16 matches.
While the visitors were on the back foot from the off, QPR 's forwards failed to produce many attacks with any real incision and Neil Warnock's men looked desperately blunt in the final third.
But with Watford offering little in response, neither team looked capable of getting the better of each other's defence in a drab opening half and it took a penalty to break the deadlock in the 38th minute.
Adrian Mariappa conceded the spot-kick after tugging at Dusko Tosic's shirt as the Serbian charged his way into the area.
Akos Buzsaky dispatched the penalty kick with consummate ease, placing the ball to the Scott Loach's right after sending the Watford goalkeeper in the opposite direction.
QPR started the second half brightly, restricting a clearly-deflated Watford, who were painfully slow out of the blocks, to long-range strikes, none of which troubled QPR keeper Radek Cerny.
But as the half wore on, Watford began to enjoy the majority of the possession and might count themselves unlucky not to have pulled one back.
The Hornets nearly found the equaliser in the 65th minute but Danny Graham sent his header just wide of the post from six yards out.
And Graham, who had already had one chalked off for offside ten minutes earlier, saw another effort cleared off the line by QPR's Peter Ramage as a spirited Watford tried to haul themselves back into the game.
But for all their endeavour, Watford were unable to find the goal they so desperately needed and now find themselves stuck just two places above the drop zone.