Highlights: Livingston 2-1 St Mirren
Kilmarnock picked up their first Scottish Premiership win under Angelo Alessio thanks to Stephen O'Donnell's breakaway goal against St Johnstone.
The Scotland full-back forced in a shot on 40 minutes after surging run out of defence from Liam Millar.
Kilmarnock were always threat on the counter and it needed a good late save from Zander Clark to deny Dom Thomas.
The visitors limited St Johnstone to very few chances, with the Perth club slumping to the bottom of the table.
Resolute Kilmarnock snuff out hosts
St Johnstone were screaming for a penalty with almost the last kick of the ball when a Stevie May shot cannoned off the arm of Gary Dicker, making a close-range block.
May came off the bench on the hour after returning to his hometown club from Aberdeen this week and added some much-needed spark to the home attack.
However, his only other attempt was kept out by a well-timed challenge from Dario Del Fabro, who impressed on his Kilmarnock debut.
The on-loan Juventus defender was instrumental in a second successive clean sheet for Alessio's side and went close to opening the scoring when his header from a Rory McKenzie free-kick flashed wide.
Kilmarnock were without Scotland duo Stuart Findlay and Greg Taylor - who is nearing a move to Celtic - but displayed the defensive discipline that was the foundation of their success last season.
As ever, Dicker and Alan Power were the dogs of war in the middle of the park, breaking up play and not letting St Johnstone settle into any kind of rhythm.
Michael O'Halloran thought he had made the breakthrough when he nodded past Laurentiu Branescu inside the six yard box but he was flagged offside from Wallace Duffy's flick.
Further frustration for hosts' followed when a free-kick on the edge of the Kilmarnock box led to the only goal. Scott Tanser's weak effort was charged down by the defensive wall and off scurried Millar down the left flank, carrying the ball all the way into the home penalty area.
The on-loan Liverpool forward had O'Donnell for company but his cut-back needed a fortunate double ricochet from panicked defenders to fall into the full-back's path before the ball was bundled in from six yards.
St Johnstone pinned the visitors back for long spells after the break but seldom looked like breaking through as a shot from O'Halloran flew over the top.
Another break from substitute Thomas almost sealed the points for the Ayrshire team but Clark saved well at full-stretch before a scruffy match, low on thrills, ended on a note of controversy with that unsuccessful penalty claim.
Kilmarnock boss Angelo Alessio celebrates his first league win in Scotland
Man of the match - Gary Dicker
BBC Scotland's John Barnes at McDiarmid Park
Kilmarnock captain Dicker helped engineer this victory from the heart of the pitch. He along with Power and El Markrini were quick to intercept passes and turn defence into attack. Dicker was assured and composed throughout.
Other contenders were Del Fabro and Alex Bruce, who formed a new central defensive partnership and were tidy and dealt with any threat comfortably. The Italian also showed he is a threat in the opposition box.
O'Halloran produced some flashes of inspiration for St Johnstone, but he failed to hit the target with the couple of chances which came his way.
'We deserved this result' - reaction
St Johnstone manager Tommy Wright: "The damage was done in the first half. It was a lukewarm performance, no energy. The tempo was unacceptable.
"In saying that, we had a perfectly good goal ruled out from Michael O'Halloran. The linesman says he gave it for Wallace Duffy offside and neither were offside. I haven't seen the incident at the end again but I don't think it's a penalty because Gary Dicker's arm is close to his body."
Kilmarnock manager Angelo Alessio: "I am very happy, because it's the first win. My team played very well today.
"Playing away against St Johnstone isn't easy but everyone played well. I want to thank our supporters for their support. We deserved this result."
