Match ends, St. Johnstone 2, St. Mirren 0.
St Johnstone missed two penalties but still recorded a dominant win over St Mirren to move into seventh in the Scottish Premiership.
David Wotherspoon and Matty Kennedy both scored from close range in the second half, but those book-ended two spurned spot-kicks.
Tony Watt had his effort saved before Liam Craig blazed high over the bar.
The result means St Mirren have now lost nine of their last 10 games, their worst run since 2013.
Oran Kearney's side sit second-bottom of the division with just four points from 10 games, while St Johnstone have recorded back-to-back victories.
Watt's happened to Tony?
After a prolific start to the season, Watt has found goals hard to come by recently. He has not scored since winning the Premiership Player of the Month for August, and will be relieved his profligacy did not cost his team on Saturday.
He had a terrific chance early on but his downward header was superbly pushed on to the crossbar by Craig Samson. The St Mirren goalkeeper produced similar heroics just before the break, this time tipping Kennedy's header against the bar after a knockdown from Wotherspoon.
Watt then had an even better opportunity in the second-half. Scott Tanser slipped a ball across goal and the defender slipped, leaving the Scotland international with an age to bury it from five yards, but somehow he put the ball past a post.
St Johnstone grew in confidence and menace, though, and eventually found the breakthrough. Drey Wright nodded the ball in the direction of Watt, who flapped at an overhead kick, but fortunately for him, team-mate Wotherspoon came to the rescue with a low finish into the corner.
Watt then had the chance to spare his own blushes minutes later when Paul McGinn was judged to have pushed Murray Davidson in the box. He stepped up but again Samson denied him.
Craig could do no better a few minutes later, ballooning his effort into the stands after Wright was scythed down by Lee Hodson.
Fortunately for the hosts, St Mirren offered very little in reply, demonstrating exactly why they are on their worst run in five years with precious little quality and an obvious lack of confidence.
Danny Mullen provided their only real spark, and had a solid claim for a penalty when brought down with the game goalless, but referee Andrew Dallas instead booked him for diving.
But with six minutes remaining, St Johnstone finally got the crucial second goal - and a second consecutive win - when Kennedy tapped in after Samson impressively pushed away a Jason Kerr header.
St Mirren struggle up front - analysis
BBC Scotland's Brian McLauchlin at McDiarmid Park
Goalkeeper Samson's performance was the only shining light on another miserable afternoon for St Mirren.
On paper, they have the players to steer them away from the treacherous position they are in. The McGinn brothers, Hodson, Adam Hammill and Ryan Flynn have all played at a high level and should be comfortable in the Scottish Premiership.
But striking options are limited and Kearney may need to look to do business in January. They did not have one attempt that troubled Zander Clark in the St Johnstone goal.
'The momentum swing didn't come'- reaction
St Johnstone manager Tommy Wright: "We dominated from the start and kept our foot on the gas. It's a fully deserved victory and it should have been by more goals.
"Tony Watt knows he could have scored one or two but I'm happy with him. He's a good lad and he's working extremely hard. He didn't deliberately miss the penalty, so I'm happy with him."
St Mirren manager Oran Kearney: "We have another very questionable penalty turned down in the first half when Danny was brought down and my players say it's stonewall. Those moments are big. To go ahead would have given us a big shot in the arm. But the momentum swing didn't come."
- 8DavidsonBooked at 54mins
- 32WattSubstituted forKaneat 76'minutes
- 33KennedyBooked at 85minsSubstituted forNydamat 87'minutes
- 2McGinnBooked at 82mins
- 15BairdBooked at 85mins
- 77HammillSubstituted forEdwardsat 75'minutes
- 4McGinnBooked at 72mins
- 22WillockSubstituted forMcShaneat 81'minutes
- 18MullenBooked at 23minsSubstituted forSmithat 62'minutes
- Andrew Dallas
- Shots on Target
Second Half ends, St. Johnstone 2, St. Mirren 0.
Corner, St. Mirren. Conceded by Scott Tanser.
Substitution, St. Johnstone. Tristan Nydam replaces Matthew Kennedy.
Jack Baird (St. Mirren) is shown the yellow card for a bad foul.
Matthew Kennedy (St. Johnstone) is shown the yellow card for a bad foul.
Goal! St. Johnstone 2, St. Mirren 0. Matthew Kennedy (St. Johnstone) right footed shot from very close range to the bottom left corner.
Attempt saved. Jason Kerr (St. Johnstone) header from the right side of the box is saved in the centre of the goal.
Paul McGinn (St. Mirren) is shown the yellow card for a bad foul.
Murray Davidson (St. Johnstone) wins a free kick in the defensive half.
Foul by Paul McGinn (St. Mirren).
Substitution, St. Mirren. Ian McShane replaces Matty Willock.
Attempt missed. Scott Tanser (St. Johnstone) left footed shot from outside the box misses to the left.
Corner, St. Johnstone. Conceded by Craig Samson.
Attempt saved. Murray Davidson (St. Johnstone) right footed shot from outside the box is saved in the bottom left corner.
Delay over. They are ready to continue.
Delay in match Christopher Kane (St. Johnstone) because of an injury.
Christopher Kane (St. Johnstone) wins a free kick in the attacking half.
Foul by Alfie Jones (St. Mirren).
Foul by Scott Tanser (St. Johnstone).