With Amiens on the back foot, it was no surprise that PSG grabbed a 4-3 lead in the 74th minute.
Mauro Icardi popped up at the far post and tapped in a fine low cross by Juan Bernat.
But the visitors then missed several gilt-edged chances with Edinson Cavani, who was looking for his 200th goal for PSG in all competitions, particularly guilty of poor finishing.
His astonishing miss in the dying minutes was punished moments later at the other end.
Guirassy levelled with a fine finish from inside the penalty area after he was put through by substitute Quentin Cornette.
In the evening’s most entertaining fixture, ninth-placed Girondins Bordeaux missed a chance to move into the top six as they were held to a 2-2 home draw by Dijon.
The visitors dropped one place to 18th.
Mounir Chouiar fired Dijon ahead early on when he capped a fast break and then salvaged a point for the visitors in the closing stages with a delightful shot.
That was after Bordeaux’s Hwaing Ui-Jo and Jimmy Briand had cancelled out his opener.
Bottom team Toulouse are staring at relegation after a 2-0 home defeat by Nice, who are eighth, left them 14 points adrift of the safety zone.
Nimes beat visiting Angers 1-0 to climb out of the bottom three.
Marseille visit fourth-placed Lille and Stade Reims are at home to Rennes, who are third, in Sunday’s stand-out fixtures.
Reuters/NAN