Match ends, Heart of Midlothian 0, Kilmarnock 1.
Scottish Premiership leaders Hearts slumped to a second successive defeat thanks to Ross Millen's first goal for Kilmarnock.
Hearts had the slightly better of the 72 minutes before Millen fired a powerful drive low under the body of goalkeeper Zdenek Zlamal.
Chris Burke, who set up the goal, was denied within two minutes by Zlamal.
Hearts had the better of the chances thereafter but lacked a finishing touch.
It leaves Craig Levein's side only one point ahead of reigning champions Celtic, who can go top if they win away to Livingston - one of two games they have in hand over the Edinburgh outfit.
Kilmarnock move up to third - two points behind their hosts - after ending their own run of three games without a win and extending their unbeaten run at Tynecastle to three games.
Killie's changes come up trumps
Hearts' four-game run without a win - all without scoring a goal - has coincided with the loss of several key players, with the absence of Scotland international Steven Naismith and fellow striker Uche Ikpeazu being particularly felt during four games without a goal.
So it was to be again against a well-organised visiting side they had not scored more than once against in their last six meetings.
Levein made four changes from the side that were thumped 5-0 last weekend by Celtic, but it was counterpart Steve Clarke who sprung the bigger surprises.
Jamie MacDonald was replaced with Daniel Bachmann despite it being a week when he was recalled to the Scotland squad, the goalkeeper perhaps paying for last weekend's loss to Aberdeen.
Northern Ireland winger Jordan Jones was also dropped to the bench and Scotland right-back Stephen O'Donnell was an absentee through injury.
Jones' replacement, Mikael Ndoli, was immediately involved as Hearts had the first of a series of appeals for a penalty turned down after his challenge on Callumn Morrison.
Kilmarnock raced up the other end and Burke's shot was blocked superbly by Zlamal after the winger was found in the clear by Aaron Tshibola's defence-splitting pass.
That set the tone for the game - flowing moves, quick counter-attacks, some clever play but few clear-cut chances.
Despite their recent hiccups, Clarke's side had only lost one of their six away games this season and they put on another resolute display on the road.
When Arnaud Djoum did split the visiting defence with a fine pass just before the break, Bachmann did well to save from Ben Garuccio, while Steven MacLean was thwarted by an offside flag when Hearts finally did find the net.
The stage was set for Millen to make the most of his chance to start thanks to O'Donnell's injury as he beat Zlamal to score his first goal for Kilmarnock since his surprise move from amateurs Queen's Park this summer.
Killie steadfast, Hearts must regroup - analysis
BBC Scotland's Brian McLaughlin at Tynecastle Stadium
With neither side recording a win on their previous three matches this was always going to be a tight affair and, over the piece, it was Kilmarnock who were able to make the best of the few clear-cut opportunities.
Despite his advancing years, Kilmarnock striker Kris Boyd showed throughout that he is more than a handful for Premiership defences, but it was the Kilmarnock defence who were the real heroes on the day.
Kirk Broadfoot and Stuart Findlay had an outstanding 90 minutes, with Greg Taylor and Millen, who raced from one end of the pitch to the other to score the only goal of the game, making up the back four for Killie.
Hearts will play better and lose games, but without the services of Christophe Berra, John Souttar and talisman Steven Naismith, they lose a critical part of their team.
The international break is coming at the right time for Levein to give his beleaguered squad some time off and come back refreshed for what will be a busy spell of fixtures up to the end of December.
- 17GaruccioBooked at 83minsSubstituted forMitchellat 86'minutes
- 38MorrisonSubstituted forMcDonaldat 68'minutes
- 5HaringBooked at 19mins
- 15WightonBooked at 79mins
- 18MacLeanSubstituted forClareat 83'minutes
- 22MillenBooked at 74mins
- 29BurkeSubstituted forMcKenzieat 75'minutes
- 12NdjoliSubstituted forWilsonat 90+2'minutes
- 9BoydSubstituted forJonesat 79'minutes
- Don Robertson
- Shots on Target
Second Half ends, Heart of Midlothian 0, Kilmarnock 1.
Foul by Djoum (Heart of Midlothian).
Jordan Jones (Kilmarnock) wins a free kick on the left wing.
Substitution, Kilmarnock. Iain Wilson replaces Mikael Ndjoli.
Attempt missed. Olly Lee (Heart of Midlothian) right footed shot from outside the box is just a bit too high from a direct free kick.
Sean Clare (Heart of Midlothian) wins a free kick in the attacking half.
Foul by Aaron Tshibola (Kilmarnock).
Hand ball by Mikael Ndjoli (Kilmarnock).
Attempt missed. Sean Clare (Heart of Midlothian) right footed shot from outside the box is close, but misses to the left.
Attempt blocked. Craig Wighton (Heart of Midlothian) header from the centre of the box is blocked.
Foul by Michael Smith (Heart of Midlothian).
Jordan Jones (Kilmarnock) wins a free kick in the defensive half.
Substitution, Heart of Midlothian. Demetri Mitchell replaces Ben Garuccio.
Ben Garuccio (Heart of Midlothian) is shown the yellow card.
Substitution, Heart of Midlothian. Sean Clare replaces Steven MacLean.
Attempt missed. Aaron Tshibola (Kilmarnock) right footed shot from outside the box is too high from a direct free kick.
Mikael Ndjoli (Kilmarnock) wins a free kick in the attacking half.
Foul by Jimmy Dunne (Heart of Midlothian).
Attempt saved. Craig Wighton (Heart of Midlothian) right footed shot from the centre of the box is saved in the bottom left corner.