Bristol City striker Nahki Wells scored the only goal of the game to condemn relegation-haunted Plymouth to a fifth home Championship defeat without scoring.
The Robins grabbed a 57th-minute winner when Jason Knight drove at goal and teed up Anis Mehmeti whose shot was acrobatically saved by Michael Cooper at full stretch.
The Argyle keeper then managed to save substitute Mark Sykes’ close-range follow-up but the ball looped up and substitute Wells nodded in on the line.
Plymouth were reduced to 10 men when midfielder Alfie Devine was sent off for a second bookable offence in the 78th minute.
Bali Mumba came closest to scoring from one of Argyle’s three early corners, volleying just over from the edge of the box.
Devine made a superb break from his own half to set up Ryan Hardie on a 12th-minute counter-attack but the Scottish striker was wide with his 20-yard angled shot on the run.
City goalkeeper Max O’Leary was called into action from Argyle’s next attack, picking Morgan Whittaker’s shot out of the air after a fine Adam Forshaw pass down the right wing.
Despite their pressure Argyle could not find a breakthrough, with a handful of players failing to connect with another Forshaw corner as it flew across the face of the visitors’ goal in the 20th minute.
Argyle’s best chance came on the half-hour when top-scorer Whittaker let fly with a thundering volley from the left after latching on to Matt Sorinola’s cross from the right. The ball flew just over O’Leary’s crossbar.
Cooper had to make a brilliant one-handed save to deny Bristol City forward Scott Twine as he raced onto a through ball from skipper Matty James. Twine tried to lift the ball over Cooper, who just managed to get enough on the ball to turn it over.
George Tanner made a chested clearance at the far post to deny Argyle as Sorinola again sent over a superb cross from the right.
Knight forced a near-post save from Cooper at the start of the second half as Bristol City continued from where they had left off, in the ascendancy.
O’Leary made a good save with his feet in the 70th minute as Whittaker cut in from the right and shot from close range.
Cooper made another full-stretch stop to deny Wells a second goal after 76 minutes as the striker broke into the box and let fly with a low angled drive.
Devine received a second yellow card following a foul on Tanner and Plymouth never really looked like threatening a late equaliser.