At a glance
The dominant Edinburgh side surged eight ahead of their Glasgow rivals at the summit of the Scottish Premiership to bolster their early-season championship claims and deepen the struggles around Brendan Rodgers' side.
A superb goal from Kyziridis and a spot-kick from Shankland gave the Hearts team a two-goal advantage that the title holders could not overcome.
The young defender - among three youth players in the Celtic starting lineup - scored an own goal in the early stages to put the home side ahead at a bouncing Tynecastle, and it was the youngster's infringement that led to the penalty.
A stylish finish from McGregor of the season had quickly cancelled out Hearts' opener, and the Swedish attacker almost put Rodgers' team in front, opting for finesse over power and allowing Alexander Schwolow to save from close range.
But Derek McInnes' irrepressible Hearts seized control again to consign the visitors to back-to-back losses for the initial occasion since last year.
It also gives the Hearts a commanding advantage at the summit.
The last time they were this far ahead was in 2005-06 under their former manager, when they ended as runners-up - a rare instance that a team has failed to win the title having held such a lead in the last three decades.
The Hearts coach, whose former team were second to Celtic on multiple times, has been working hard to play down championship discussions, as the club seek their maiden league title since 1960.
The Celtic boss has experienced this previously at Celtic - both flawless and stuttering starts to a season. He's never ended as runner-up.
But on Sunday's evidence, this Hearts team showed they deserve serious consideration.
The Edinburgh side started with the self-assurance of a side unbeaten in the league this season - the popular attacker delivered a ball for the striker to fire off target.
Celtic didn't aid their cause with some uncharacteristic carelessness in possession and they buckled under their first real examination.
A headed effort from Braga was tipped onto the woodwork by the Celtic keeper and the follow-up from Shankland was turned into the net by the unfortunate Murray, in for the absent center-back.
Celtic grew into the contest and started stringing passes together. From one such move, the midfielder released Tierney to square for the captain, who rolled in.
Apart from the opportunity for Nygren, the visitors struggled to create much for striker Kenny or his replacement Shin Yamada amid the absence of injured forwards Kelechi Iheanacho and Daizen Maeda.
Hearts regained their intensity and adaptability in creating chances in the opposition half. Kyziridis, one of the finds of the club's relationship with shareholder Tony Bloom's Jamestown Analytics, struck low past the goalkeeper from the just outside the area.
Almost straight away, the defender fouled the midfielder in the inside right channel and Shankland converted. And it could've been an even more handsome win, had replacement Ageu not been denied by Schmeichel.
The visitors' performance after the break was somewhat summed up in two incidents involving big-money recruit Engles.
The midfielder's wayward free-kick delivery was in sharp opposition to his European display in the continental victory over Sturm Graz and the national team player was then booked for a professional foul.
The Hearts manager: "You see how hard the players work, the togetherness. That's not sufficient on its own to win games week in, week out.
"Our strength lies in, is good technical ability. You're witnessing it from a lot of players who have been here before. Some of the new signings are eager to show that.
"We've got a good thing going at the minute, but it's only three points. It's crucial for us to keep winning. We've got loads to do, loads to do. Following the initial fixtures is typically a benchmark of where you are."
The Celtic boss: "It's a really poor goal from our perspective. We failed to push up when the play was recycled as a line so when they play it, they ought to be caught offside but didn't. We have got to improve with the shot.
"There's still so many points to play for. It's only the beginning. It's only nine games in. Clearly, being eight adrift is not ideal. The comfort is there's so many games to play.
"Our attention must turn on the present and look to achieve greater stability and better performance in our play."
Celtic are back at home on Wednesday against promoted side Falkirk (19:45 GMT). At the identical hour in the top division, Hearts are at their opponents' ground.
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