The result finally destroyed any lingering notions the club had of snatching a late place in the top six and indeed ignited fears that Saints could yet get drawn into the relegation battle as the heat intensifies at the foot of the SPL table.
Here's what the media made of the match;
St Johnstone kept up their chase for a European place and all but ended St Mirren's chances of a top-six finish with a classy victory in Paisley.
Lee Croft fired Steve Lomas' side in front after only two minutes with a long-range effort.
Defender David McCracken hit the second from close range after goalkeeper Craig Samson failed to deal with a corner.
The third goal arrived in the closing stages when Francisco Sandaza slid the ball under the home goalkeeper.
The home side suffered a pre-match blow when hitman Steven Thompson was only fit enough to make the bench after picking up a thigh knock in training.
Lennon was also without crocked Kenny McLean but welcomed back defender Marc McAusland.
The big stopper fractured his eye socket against Aberdeen last month but made a swift recovery. Dougie Imrie also started.
St Mirren manager Danny Lennon backed his players to bounce back and be ready for Wednesday’s William Hill Scottish Cup quarter-final replay with Hearts.
He said: “The boys will be back in on Sunday morning and we will get it out of their system.
“We will sit down as a group and start preparing for Wednesday evening. It’s a huge match and I’m sure they will bounce back for that one.”