Preston substitute Neil Mellor stepped off the bench to fire Alan Irvine's Coca-Cola Championship strugglers to a potentially crucial win over high-flying Watford.
Former Liverpool striker Mellor had been on the pitch for just two minutes when he lashed home from close range to settle a close affair at Deepdale and end a three-game losing streak for the home side.
Adrian Boothroyd's side have the best away record in the whole division but were outplayed for the majority of the clash by Irvine's men before Mellor's 75th-minute finish which boosted the Lilywhites' hopes of avoiding relegation.
Irvine's side have a tough run of fixtures over the next six weeks - which sees them take on West Brom, Stoke twice and Watford again - but they showed enough commitment and organisation to suggest that they have enough to survive.
Marlon King took his place in the Watford side after the club turned down a £4million bid from Premier League strugglers Fulham this week, while Richard Chaplow and Chris Brown were both handed debuts by Irvine after their moves from West Brom and Norwich respectively.
King was subdued throughout and with reports of a fresh bid circulating his future is uncertain.
North End's left winger Lewis Neal had the first effort of the match but his ambitious strike from 35 yards sailed harmlessly over after a crisp passing move from the home side.
Neal was at the hub of everything about Preston's bright start and, after he did brilliantly to keep the ball in on the touchline, his low cross was dummied by Chaplow but Brown's effort was well blocked by Jay DeMerit.
Chaplow was then robbed by Jobi McAnuff 25 yards from goal and only a fingertip save from Andy Lonergan kept out his low drive before Watford defender Matt Jackson was lucky not to be sent off for cynically hauling down the rapid Karl Hawley after he had misjudged a long ball.
The former Wigan man was only booked by referee Scott Mathieson for the foul and Boothroyd's side almost rubbed salt into the wound by scoring instantly.
Tommy Smith's cross caused havoc in the Preston defence and Darius Henderson somehow found the ball at his feet just eight yards from goal.
He got a shot away but Lonergan reacted superbly to palm the ball away and deny Henderson his 11th goal of the season.
The second period struggled to get going as both sides squandered possession far too cheaply with Simon Whaley's blocked shot after a bright Sean St Ledger run the only highlight of the opening 15 minutes.
Another long-range drive from Neal forced a good save out of Richard Lee as the hosts controlled the majority of the play with Watford content to use the pace of King and McAnuff on the break.
Chaplow and Brown were both replaced as they felt the effects of a lack of first-team football and it was Brown's replacement Mellor who found the breakthrough.
Whaley's deep cross from the right was turned back into the danger zone by Neal.
Mellor hit his shot straight at Lee but, as the ball rebounded back to him, placed his second effort right into the top corner.
Watford sub John-Joe O'Toole then shot narrowly wide from 25 yards before Henderson headed straight at Lonergan.
Goal: Mellor (75) 1-0.
Preston North End (4-4-2): Lonergan; St Ledger, Mawene, Chilvers, Davidson; Whaley, Chaplow (Carter, 75), McKenna, L Neal; Brown (Mellor, 73), Hawley. Substitutes not used: C Neal (gk), Sedgwick, Ormerod.
Watford (4-4-2): Lee; Doyley, Jackson (Mariappa, 79), DeMerit, Stewart; Smith, Williamson, Francis (O'Toole, 76), McAnuff; King, Henderson. Substitutes not used: Poom (gk), Priskin, Ellington.
Referee: S Mathieson (Cheshire).
Booked: Preston North End Davidson, Whaley; Watford Jackson.
Man of the match: Neal.