St Johnstone enhanced their prospects of a fourth successive top six finish by dominating a Paisley side which is in dire danger of losing its Premier status.
Only once did the Buddies pose a serious threat to Perth keeper Alan Mannus, who clocked-up his fourth clean sheet in five games.
With Northern Ireland’s friendly looming with Scotland in midweek, he will be hoping that impressive track record has not gone unnoticed by international manager Michael O’Neill.
On-loan Dundee United striker Brian Graham impressed in his first start since mid-January, scoring once, hitting the post and he could easily have had a hat-trick with midfielder David Wotherspoon providing a steady stream of crosses from the flanks.
It was from a second half Wotherspoon corner that centre-back Steven Anderson stole round the back and repeated their combination for the memorable Scottish Cup final opening goal.
The three points saw the McDiarmid side nudge aside tumbling Hamilton Accies to occupy fifth place and now they are closing in on Dundee United.
But St Mirren are a club in crisis, with under threat Motherwell and Ross County opening-up a gap.
Seven days after crashing to an unexpected 3-0 defeat to Partick Thistle, Perth playmaker Wotherspoon admitted: “It was a must win to push for a top six place and we went about it the right way.
“It wasn’t us last week. It just wasn’t like us. But, we bounced back and we could have scored a couple more goals.
“We are just delighted to get the win.
“Our aim is to catch Dundee United. We need to look ahead. It is not unrealistic to catch them. We have enough games left to push on.
“United have had a difficult run of games recently and we will look to capitalise on that.
“That might play a part but we just need to focus on ourselves.”
Reflecting on his corner kick and Anderson’s mirror image header of the May 17 strike against Dundee United, he said: “The second goal was familiar. I just put the ball at the back post knowing he is always about that area.
“We don’t really work on it but luckily Ando was at the back stick to put it away.”
The Perth Saints should have won more handsomely against a Buddies side drained of belief.
They seized the initiative from the opening minutes and held onto it, although it did require a brilliant reflex save from an otherwise idle Mannus to prevent Viktor Genev volleying in a 67th minute strike to halve the deficit.
Perth manager Tommy Wright was rewarded for restoring Graham for the first since mid-January and defender Frazer Wright was rock solid at the back after concussion sustained against Kilmarnock.
Loan star Graham was thwarted by a timely Jason Naismith block in the sixth minute and the chances kept coming.
He headed wide from a Wotherspoon cross and hammered a tight angled shot at the keeper after a brilliant sweeping Perth move and a Dave Mackay cross.
Graham was out of luck with a delicious curling 20-yard shot which evaded the keeper but clipped the post and then he headed wide from a promising position.
But the striker persevered and was rewarded when the breakthrough was made in the 33rd minute, with defender Jim Goodwin guilty of giving him too much room in the danger area.
The centre controlled Wotherspoon’s delivery and had time to take a couple of touches before prodding it past the exposed keeper.
After the break Graham couldn’t believe he had failed to net with a diving header from another Wotherspoon cross and Anderson came close before his 67th minute header.
Perth boss Wright confirmed the players had stuck to the game plan and got their reward.
And assessing Wotherspoon’s contribution, he said: “I’ve been pleased with David since I brought him to the club. I gave him some stick in the second half because I felt he could have put the ball in a couple of times.
“But David is a wonderful footballer. It was a great ball for both goals.”
He added: “It was important to start well and we did that. We knew they play a high line and we’d talked about getting balls in behind them and when we got into the last third to put balls in the box.
“We did that. Second half we could have done it a wee bit more. We got the second goal and I think we deserved that.”
He added: “We’re pleased Brian has come in and scored a goal and we’ve got a clean sheet. We’re up to fifth and it was just what we needed.
“He’s had a few chances today and he gets into good positions. It was a decent ball in from Wotherspoon.
“The ball dropped to his feet and he kept calm before sticking it away. He was unlucky with the one that hit the post and maybe should have done better with the header.
“But he had a good day and I’m really pleased with his contribution.”
“We emphasised to the players every win is vital. Winning opens a gap on Kilmarnock, Dundee and moves us above Hamilton who we have next.”
St Mirren’s caretaker coach Gary Teale was brutally frank.
He said: “We were awful. We were outfought and it was extremely disappointing.
“I’m the manager, I will take responsibility but that performance just wasn’t good enough.
“It was one of the worst of the season.”