Scottish Premiership leaders Celtic booed off after defeat by Hearts
First-half goals from Lawrence Shankland and Stephen Kingsley gave Hearts their first league win at Celtic since 2007, prompting furious Hoops fans to turn their wrath on the club's board of directors.
It was March 2013 when Celtic last lost consecutive league games, against Motherwell and Ross County.
Shankland's free header and Kingsley's 25-yard free-kick saw Hearts end a 14-match losing run at Celtic.
It also secured their first victory in any competition at Parkhead in 25 games, since Michael Stewart's penalty earned a League Cup win in 2009.
Celtic's surprise loss, on the back of last weekend's loss at Kilmarnock, leaves them five points ahead of Rangers in the Premiership.
But their Glasgow rivals have two games in hand.
With the Green Brigade ultras group still banned, the atmosphere among the home fans was again flat but it turned angry for a spell late in the second half as Celtic toiled.
One fan in the main stand sparked wider dissent when he shouted towards the Celtic directors, leading to chants of "sack the board" from around the stadium and more personal songs aimed at chairman Peter Lawwell.
The club's close-season recruitment again came into question with only one of their eight summer signings among the 16 players to feature.
Elsewhere in the Premiership, Dundee clinched a 1-0 victory at Ross County deep into stoppage-time when Joe Shaughnessy scored with the last touch of the game.
Luke McCowan's free-kick came back off the post and went in off the Dundee captain.
The other two games both finished goalless but only after missed penalties in each.
St Mirren's Mark O'Hara had his spot-kick early in the second half saved by Liam Kelly as Motherwell secured a goalless draw.
Bottom of the table Livingston also wasted the chance to pick up a much-needed win against Kilmarnock after Bruce Anderson missed a late penalty when Stuart Findlay was penalised for handball.