Grant Brebner piled more agony on bottom of the table Partick with a last minute winner for Hibernian.
Hibs started the match the stronger side and in the opening minutes had Kenny Arthur in the Thistle goal pulling off some fine saves from O'Connor and Dobbie.
Thistle were awarded a free kick in the eighth minute but Derek Fleming's shot from 25 yards out went across the goal, was missed by the Hibs defenders but Mitchell's return shot was Wasted as it went into the side netting.
Play became very scrappy and referee Rowbottom was hard pressed to keep the match under control with some strong tackling going in from both sides.
Hibs had a golden opportunity to take the lead in the 32nd minute when they were awarded a free kick 20 yards out.
Gary O'Connor took the kick and his fierce shot went round the five man Thistle defensive wall and the unsighted Jags keeper Kenny Arthur pulled off an outstanding save low to his right hand post.
In the 47th minute referee Rowbottom enraged the Thistle fans and players when he turned away their claims for a penalty kick after Omand had tangled with Fleming inside the penalty box with the Thistle player being spread eagled on the grass.
Thistle fans thought they and taken the lead in the 54th minute when Gerry Britton fired a low shot past past Andersson in the Hibsâ€™ goal but the referee and assistant judged him to be offside.
Both sides made substitutions in the 72nd minute with Thistle replacing an out of form James Grady with Andy Fleming and Hibs swapping Dobbie for Riordan.
Suddenly after taking the field Riordan ran onto a through pass in the 76th minute with no one to beat but keeper Arthur but the keeper ran out narrowed the angle and plucked the ball from Riordan's feet.
Four minutes later Riordan again wasted a golden opportunity when from only eight yards out he shot wide from an O'Connor cross.
Hibs broke the deadlock in the 89th minute when following pressure on the Thistle defence they were awarded a free kick 20 yards out.
Riordan took the kick into the penalty area and somehow Brebner managed to get his toe to the ball and tap home from six yards out.
After the match Thistle Manager Gerry Collings said: "I really feel sorry for my players and fans. We played well and dominated much of the match but were unable to convert our chances." And Hibs' boss Bobby Williamson said he was delighted with the result and would take a goal whenever it comes.