At a glance
The dominant Edinburgh side powered eight ahead of Celtic at the summit of the Scottish Premiership to bolster their early championship claims and worsen the malaise around Brendan Rodgers' side.
A superb goal from Kyziridis and a spot-kick from Shankland gave the Hearts team a 3-1 lead that the reigning champions could not overcome.
The young defender - among three youth players in the Celtic XI - slashed into his own net in the early stages to put the home side ahead at a energetic their home ground, and it was the youngster's infringement that led to the penalty.
A stylish finish from McGregor of the season had swiftly equalized the first goal, and the Swedish attacker almost put Celtic in front, choosing placement over power and allowing the Hearts keeper to save from close range.
But Derek McInnes' irrepressible Hearts seized control again to hand the visitors to back-to-back losses for the initial occasion since last year.
It also gives the Edinburgh side a commanding advantage at the summit.
The last time they were so far clear was in the 2005-2006 season under their former manager, when they ultimately finished second - a rare instance that a team has not secured the title having held such a lead in the last three decades.
The Hearts coach, whose Aberdeen side were runners-up to the champions on four occasions, has been working hard to downplay championship discussions, as the club seek their first top-flight crown since the 1960s.
Rodgers has experienced this previously at Celtic - both perfect and shaky beginnings to a season. He's yet to finish second best.
But on Sunday's evidence, this Edinburgh outfit showed they need to be taken seriously.
The Edinburgh side started with the self-assurance of a side unbeaten in the league this season - fans' favourite Kyziridis delivered a ball for the striker to stab wide.
The Glasgow team didn't aid their cause with some unusual sloppiness in possession and they faltered under their initial test.
Claudio Braga's header was touched on to a post by Kasper Schmeichel and Shankland's return ball was turned into the net by the unfortunate Murray, in for the injured Cameron Carter-Vickers.
The away side grew into the contest and started stringing passes together. From a flowing attack, the midfielder released the full-back to set up McGregor, who slotted home.
Apart from the Nygren chance, the visitors struggled to create much for lone frontman Jonny Kenny or his substitute Yamada amid the absence of injured forwards their key strikers.
Hearts regained their intensity and versatility in creating chances in the opposition half. The Greek forward, a standout performer of the club's scouting network, struck low past Schmeichel from the edge of the box.
Almost straight away, Murray tripped Braga in the right side of the box and the penalty taker scored. And it could've been an even more handsome win, had replacement Ageu not been stopped by the shot-stopper.
The visitors' performance after the break was partially encapsulated in a couple of moments involving big-money recruit Engles.
The set-piece from Engles delivery was in stark contrast to his midweek exploits in the continental victory over their Austrian opponents and the Belgium international was then booked for a cynical foul.
Hearts head coach Derek McInnes: "You see how hard the players work, the team spirit. That's not always enough to win games week in, week out.
"What we have got, is skillful players. You're seeing that from multiple individuals who have been here previously. Some of the new signings are keen to demonstrate their quality.
"We're in a positive moment at the minute, but it's only three points. It's crucial for us to keep winning. We've got loads to do, plenty to improve. Following the initial fixtures is normally an indication of your standing."
The Celtic boss: "It's a really poor goal from our perspective. We failed to push up when the ball went back as a line so when they play it, they should have players offside but weren't. We have got to improve with the shot.
"Plenty of matches to play for. It's still so early. It's just nine matches. Clearly, being eight adrift is not ideal. The positive is there's so many games to play.
"We now have to focus on the here and now and look to find more consistency and better performance in our play."
The Glasgow club are back at home on Wednesday against newly-promoted Falkirk (evening kick-off). At the identical hour in the top division, the Edinburgh outfit are at St Mirren.
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