Livingston's 14-game unbeaten run came to a shuddering halt as St Johnstone emerged 2-1 winners from this dress rehearsal for the Betfred Cup final.
David Martindale endured his first taste of defeat as a manager courtesy of a stunning free-kick by Scott Tanser and a clinical Shaun Rooney header.
The Saints' margin of victory could have been even more handsome in this Scottish Premiership contest, with Jason Kerr passing up a golden opportunity in the opening stages and Stevie May seeing his second-half penalty saved by Max Stryjek.
Although Scott Pittman pulled one back for the hosts, Callum Davidson's impressive outfit held firm to claim an unlikely triumph and land the first blow ahead of their rematch with the Lions on February 28.
The visitors were immediately in the front foot at the Tony Macaroni Arena, with skipper Kerr volleying narrowly over the bar after meeting a deep David Wotherspoon delivery.
That was as close as either side would come until the cusp of half-time.
A hefty challenge from Aaron Taylor-Sinclair - not his first of the afternoon - on Kane gave Tanser a golden opportunity to break the deadlock from the edge of the box, and the wing-back superbly found the corner of the net with his free-kick.
Martindale replaced Alan Forrest with Jay Emmanuel-Thomas at the break in a bid to spark the home side's attack into life. However, instead he saw Livi slip further behind five minutes into the second period.
Liam Craig was the creator, sweeping a fine free-kick onto the head of Rooney, whose clinical header from 10 yards left Stryjek stranded and took his tally for the campaign to three.
St Johnstone should have put the game to bed when Rooney was hauled down in the box as he sought to meet another Craig delivery. Referee Euan Anderson pointed to the spot but May, on as a substitute, saw his spot-kick saved by the legs of Stryjek.
And an unnecessarily nervous finale for the Perth men was assured when Pittman halved the arrears with a super glancing header from a Nicky Devlin cross.
However, St Johnstone held firm to inflict a first defeat on Livi since their 1-0 reverse against St Mirren on November 21.
What the managers said:
Livingston boss David Martindale: "I don't feel any different and I won't be changing anything that I do.
"We still trust the work, trust the process and I'll be doing the same things I've done for five years. We don't get too high when we win games and we won't get too low now we've lost one."
St Johnstone boss Callum Davidson: "We didn't really work on tactics for today. We focused on the attitude and commitment because that's what you need to get a result at Livingston. That was the most pleasing thing for me.
"Livingston are 14 games unbeaten, they are a good side and they battle for everything. So we knew we had to come here, fight just as hard as them or even harder - that's what got us the result."