Preston's Coca-Cola Championship play-off hopes hang in the balance after second-half goals from Sylvan Ebanks-Blake and Barry Hayles earned Plymouth a 2-0 win at Home Park.
North End started the day in fourth place but their promotion destiny is now out of their hands after a fifth defeat in six matches pushed them down to eighth in the table and one point adrift of the play-offs.
Paul Simpson's side could have few complaints as they showed a distinct lack of enterprise and Argyle deservedly broke the deadlock in the 77th-minute.
Preston captain Graham Alexander was adjudged to have handled the ball inside the box and Ebanks-Blake made no mistake with the penalty.
Top scorer Hayles made sure of the points five minutes from time with a close-range finish for his 14th goal of the season.
Plymouth dominated but they were unable to make the breakthrough as Preston defended with determination.
Argyle came close through Hayles midfielder Akos Buzsaky and defender Marcel Seip in the first-half while North End never looked capable of getting the goals that could see them secure a top six spot by the end of the day.
Hayles fired narrowly wide in the third minute from Peter Halmosi's far-post corner before Buzsaky forced Wayne Henderson into action with a shot from the edge of the area.
Seip headed another Halmosi corner straight at Henderson midway through the half.
Preston's best chance came in the 17th-minute when Danny Pugh got on the end of Brett Ormerod's cross but he put his header from 10-yards out over the crossbar.
Plymouth boss Ian Holloway resisted the temptation to name an unchanged side for the fourth consecutive game.
He made one change as fit-again keeper Romain Larrieu replaced Luke McCormick to make his first appearance since returning from his loan spell with League One side Gillingham.
Simpson stuck with the same starting XI that lost at home to Leicester.
Argyle came close again early in the second-half through Gary Sawyer and David Norris narrowly missed the target on two occasions.
Chris Sedgwick spurned Preston's best chance of the second half when he headed straight at Larrieu.
Teams:
Plymouth Larrieu, Connolly, Seip, Doumbe, Sawyer,Buzsaky (Gallen 75), Norris, Nalis, Halmosi, Ebanks-Blake,Hayles.
Subs Not Used: McCormick, Timar, Djordjic, Fallon.
Booked: Sawyer.
Goals: Ebanks-Blake 77 pen, Hayles 85.
Preston Henderson, Alexander, St. Ledger, Chilvers, Hill,Sedgwick (Whaley 73), Davidson, Soley, Pugh,Nugent (Ricketts 73), Ormerod (Agyemang 82).
Subs Not Used: Lonergan, Wilson.
Booked: Soley, Alexander.
Att: 13,813
Ref: D Gallagher (Oxfordshire).