Hearts were denied top spot in the Ladbrokes Premiership as Graham Cummins earned St Johnstone a 1-0 victory at McDiarmid Park.
The Irishman knocked in a Liam Craig shot in the 58th minute to earn Saints successive wins over Hearts after last month's Betfred Cup success.
Hearts head coach Robbie Neilson was sent to the stand late on and Callum Paterson almost grabbed an equaliser with two minutes remaining but his header crashed back off the bar.
Hearts were the dominant force in the opening exchanges and St Johnstone had goalkeeper Zander Clark to thank for keeping the scoreline blank with an impressive display.
Clark had held Sam Nicholson's weak low shot and grabbed Bjorn Johnsen's heavy touch, and Saints defender Richard Foster had been brave to block Tony Watt's shot on the turn from point-blank range with his head.
But Hearts created the game's first clear-cut opportunity in the 14th minute.
Watt freed Nicholson down the right and his square pass picked out Faycal Rherras bursting into the box, but the full-back's right-foot shot was stopped well by Clark.
A minute later, Cummins was booked by referee John Beaton for simulation, much to the delight of the Hearts fans who have seen their own players accused of diving in recent weeks.
Clark was again forced into a superb save to keep Hearts at bay with 24 minutes gone.
The ball broke in a crowded box for Jamie Walker but the Saints goalkeeper showed superb reactions to block the winger's effort low to his right.
Saints were rarely seen in attack but Murray Davidson could have done better when he mis-hit his shot bursting into the box and Cummins looped a header over the bar as the half became scrappy.
Clark was again a key figure for St Johnstone three minutes into the second period.
Davidson was booked for a foul on Nicholson and Watt's curling free-kick was heading for the top corner until Clark tipped the effort round his left-hand post.
The 24-year-old goalkeeper then punched away an Igor Rossi header under his bar from a Nicholson corner.
And in the 58th minute those saves proved crucial as Saints took the lead.
Steven MacLean found the overlapping Foster in space on the right wing and his cross was fired towards goal by Liam Craig, with Cummins applying the finishing touch from six yards.
Hearts struggled to summon a response and almost conceded a second with 20 minutes remaining but goalkeeper Jack Hamilton recovered to grab his own mistake from a Craig shot just before his fumble crossed the line.
Paterson went within a whisker of the equaliser from Nicholson's corner but it was a first defeat in four outings for the Tynecastle side.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules here