St Mirren recorded their first Scottish Premier League home victory of the season thanks to goals either side of the interval.
Buddies captain Jim Goodwin thundered in the opening goal from 40 yards.
The home side's lead was doubled when Steven Thompson laid the ball on a plate for Lewis Guy to score from close range.
Hearts' inability to put the ball in the back of the net was their downfall once more.
Things had looked promising for them early on as Callum Paterson, playing as the lone striker, twice came close to scoring within the space of 60 seconds.
His first effort, after eight minutes, was a header from six yards after Arvydas Novikovas had knocked a Ryan McGowan delivery back across goal.
But the youngster could not rise high enough to direct the header on target.
He did brilliantly moments later to fire in a powerful shot low to Craig Samson's right, but the keeper got down superbly to keep it out.
St Mirren fashioned a good chance five minutes later - Thompson playing a nice pass for David van Zanten to find Paul McGowan at the back post, but the midfielder failed to trouble Jamie MacDonald.
Paterson passed up an even better chance after 28 minutes. Novikovas drove into the box, poked it past Samson as he raced out to try to block, but Paterson's sidefooted effort was diverted wide by Paul Dummett.
A rare piece of flowing football almost produced a breakthrough for St Mirren, as Graham Carey's cross from the left was met deftly by the head of Lewis Guy, only for MacDonald to push it to safety.
But the keeper was beaten seven minutes before the break by a howitzer from Goodwin.
It looked hugely ambitious as he lined up a strike from 40 yards, but it was hit so sweetly, MacDonald could not prevent the ball flying inside his right-hand post.
Nor he could he do anything as St Mirren doubled their lead within two minutes of the restart.
Thompson got a break of the ball on the edge of the box as the home side mounted a swift counter-attack, and with great vision he rolled the ball into the path of Guy, who could not miss from just a few yards out.
Hearts were no doubt aggrieved at being two goals down, and should have had a goal back just after the hour mark, but neither McGowan nor Ryan Stevenson could turn a Danny Grainger corner into the net, with Samson stranded.
The visitors began to look more and more desperate, throwing on strikers John Sutton and Dale Carrick, but seemingly running out of ideas as to how to test Samson.
And with St Mirren content to sit back and soak up Hearts' pressure, Danny Lennon's side eventually ran out comfortable winners.