Match summary
The dominant Edinburgh side powered eight points clear of Celtic at the top of the Scottish Premiership to bolster their early-season title credentials and deepen the struggles around the Celtic team.
Alexandros Kyziridis' fine strike and a spot-kick from Shankland gave the Hearts team a two-goal advantage that the reigning champions could not recover from.
The young defender - among three youth players in the Celtic XI - scored an own goal in the early stages to put the home side ahead at a energetic Tynecastle, and it was the youngster's infringement that led to the spot-kick.
Callum McGregor's classy first goal of the season had swiftly equalized Hearts' opener, and the Swedish attacker almost put Celtic in front, choosing placement over power and allowing Alexander Schwolow to make a crucial stop.
But Derek McInnes' irrepressible Hearts regained dominance to consign Celtic to back-to-back losses for the initial occasion since 2023.
It also gives the Hearts a commanding advantage at the top of the table.
The previous occasion they were this far ahead was in the 2005-2006 season under their former manager, when they ended as runners-up - a rare instance that a team has failed to win the title after building such an advantage in the past 27 years.
McInnes, whose Aberdeen side were second to Celtic on four occasions, has been working hard to downplay title talk, as the club seek their first top-flight crown since the 1960s.
The Celtic boss has seen it all before at Celtic - both flawless and stuttering starts to a season. He's yet to finish second best.
But on the weekend's performance, this Edinburgh outfit showed they deserve serious consideration.
Hearts started with the confidence of a side undefeated in the league this season - fans' favourite Kyziridis delivered a ball for the striker to fire off target.
Celtic didn't help themselves with some unusual sloppiness in possession and they faltered under their first real examination.
A headed effort from Braga was tipped onto the woodwork by Kasper Schmeichel and the follow-up from Shankland was diverted goalwards by the unfortunate Murray, in for the absent center-back.
Celtic 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 striker Kenny or his substitute Yamada amid the unavailability of stricken attackers their key strikers.
The home team rediscovered their energy and adaptability in attacking from across the final third. The Greek forward, a standout performer of the club's scouting network, fired a low shot past Schmeichel from the edge of the box.
Immediately after, the defender fouled the midfielder in the inside right channel and the penalty taker converted. And it could've been an even more handsome win, had substitute Ageu not been stopped by Schmeichel.
Celtic's second half was partially encapsulated in two incidents involving big-money recruit Engles.
The set-piece from Engles delivery was in stark contrast to his European display in the continental victory over their Austrian opponents and the Belgium international was then yellow-carded for a cynical foul.
Hearts head coach Derek McInnes: "You see how hard the players work, the togetherness. That's not always enough to win games consistently.
"Our strength lies in, is skillful players. You're seeing that from multiple individuals who have been here before. Recent additions are eager to show that.
"We're in a positive moment at the minute, but it's only three points. It's important for us to keep winning. We've got loads to do, loads to do. After the first two rounds is normally an indication of your standing."
Celtic manager Brendan Rodgers: "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 do better with the shot.
"There's still so many points to play for. It's still so early. It's only nine games in. Clearly, being eight points behind is not what we would want. 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 promoted side Falkirk (19:45 GMT). At the identical hour in the Scottish Premiership, the Edinburgh outfit are at St Mirren.
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