St Johnstone won the battle of two League Cup semi-finalists to send Hearts deeper into the relegation mire.
Hearts had the better of the early play but could not turn confident passing into goals.
It was Saints who supplied the clinical finishing as Nigel Hasselbaink headed the opener.
The Dutch striker should have added a second, but Stevie May's second-half strike secured Saints' first away league win of the season.
Hearts' position could have been even worse had St Mirren's match against Ross County not been abandoned because of heavy rain with the Paisley side 2-0 ahead.
However, the young Tynecastle side remain 15 points behind the second bottom Buddies.
And, while manager Gary Locke will not admit it, even this early in the season, they must be preparing for life in the Scottish Championship next season.
For all their youthful enthusiasm and energised by their midweek cup win over city rivals Hibernian, they did not look, against St Johnstone at least, to have that killer quality in front of goal that would enable them to go on the kind of winning run that will save them come May.
They did start the brighter, with Danny Wilson having a header saved by keeper Alan Mannus, Jamie Walker flashing a powerful drive wide and Jason Holt squandering an opening by firing wildly over.
Hearts' keeper Jamie MacDonald had been their midweek hero and he did well to block a close-range Hasselbaink effort off his line after May had weaved his way to the by-line.
That was a warning of what was to come as a Chris Millar cross was fortuitously deflected into the Hearts box and Hasselbaink headed home from eight yards out.
Hearts responded well and right-back Jordan McGhee found himself on the end of a Walker cross but could not get enough on the ball to turn it into the net in front of goal.
The diminutive Hasselbaink should have had a second headed goal shortly before the break only to nod over, but extension of Saints' lead was only briefly delayed.
The Perth side, themselves looking to build on a League Cup quarter-final victory over Morton, made a whirlwind start to the second half and had a couple of efforts cleared off the line.
MacDonald also saved from Garry MacDonald before May did find the net.
After the goalkeeper parried clear a Millar drive, May celebrated his 21st birthday a day early by steering the ball into the far corner from 15 yards.
Still Hearts would not accept their fate, a Dylan McGowan header flashing wide, while Holt and David Smith threatened from range.
However, a defence in which Tam Scobbie proved a sturdy replacement for suspended Frazer Wright, held firm to record their third win in seven days.
Heart of Midlothian
- 01 MacDonald
- 30 McGhee
- 03 McHattie
- 02 Hamill
- 05 McGowan
- 04 Wilson
- 12 Paterson (Carrick - 58' )
- 08 Robinson (Smith - 70' )
- 07 Stevenson
- 15 Holt
- 14 Walker (Nicholson - 55' )
- 13 Ridgers
- 16 McKay
- 17 Smith
- 18 Carrick
- 20 Tapping
- 28 Nicholson
- 29 Oliver
- 01 Mannus
- 19 Miller
- 24 Easton
- 08 McDonald (Jahic - 87' )
- 02 Mackay
- 03 Scobbie
- 07 Millar
- 18 Davidson
- 11 Hasselbaink (Edwards - 75' )
- 17 May
- 10 Wotherspoon (Caddis - 90' )
- 04 Cregg
- 14 Edwards
- 15 Banks
- 16 Caddis
- 20 Brown
- 25 Jahic
- 27 Fallon
Ref: Bobby Madden