Pep Guardiola’s side had got off to a flying start in Lisbon going ahead thanks to a fourth minute goal from Phil Foden.
The Blues – who handed teenage defender Jahmai Simpson-Pusey a full debut – dominated the first half carving out a host of other chances.
But, out of nowhere, Gyokeres struck to level affairs late in the first half before Sporting then scored twice within three minutes at the start of the second half through Maximiliano Araujo and Gyokeres, via a penalty, to seize control.
Erling Haaland then saw a penalty hit the bar before Gyokeres struck from the spot at the other end for the second time to seal his hat-trick with City suffering our first European loss of the season and third straight defeat.
What happened
The action in the Portuguese capital was preceded a sombre minute’s silence in honour of the many people who lost their lives in last week’s dreadful flooding around the Valencia region.
There was also a huge tifo adorning one side of the stadium in honour of Sporting boss Ruben Amorin who leaves next week to take up the reigns at Manchester United.
Once the action started though it was City who got straight onto the offensive and with less than four minutes on the clock we were ahead through Foden after a high octane start.
The England international latched onto a poor pass by Sporting’s Hidemasa Morita and Foden needed no second invitation to lash home a superb left footed shot from outside the box to register what was his third goal of the Champions League campaign.
Two minutes later it was almost two with City teasing an opening for Mateo Kovacic who saw a goal-bound shot deflected wide to Sporting’s relief.
There was then a huge scare at the other end. Savinho relinquished possession to allow Sporting dangerman Gyokeres to race clear up field.
However, Ederson stood tall and denied the striker’s attempted chip with a comfortable save.
Back stormed City with Sporting keeper Franco Isael diving to palm away Haaland’s fierce shot – all this within the first 10 minutes of the game.
City’s movement and passing were causing Sporting constant headaches and the only frustration was that that dominance hadn’t been rounded off with more goals.
Gyokeres then came to Sporting’s rescue at the other end on 28 minutes, clearing a Haaland header off the line from what was City’s eighth corner inside the first half hour.
Two minutes later Israel then produced a superb diving save to deny Haaland’s crisp first-time volley from another inviting Foden cross.
Another exquisite piece of skill from Foden via an instinctive backheel then put in Bernardo with the skipper’s low drive whistling inches wide of the target.
The fear was that City could come to rue those missed opportunities and, out of nowhere, Sporting drew level on 38 minutes.
Dangerman Gyokeres was found by Geovany Quenda and made a neat run to edge ahead of the City defence and hold off Simpson-Pusey before beating Ederson at the far post for his 21st goal of the season.
City would have come out for the second half seeking to reassert control. Instead, straight from the kick-off Sporting stuck to take the lead.
A fine move from the hosts saw Pedro Gonçalves deliver a fine pass into the path of Maximiliano Araujo and he needed no second invitation to find the target from inside the box.
Within 60 seconds it got worse as Sporting were awarded a penalty after Gvardiol was adjudged to have elbowed Francisco Trincão in the box.
Gyokeres made no mistake from the box, rifling home into the top right-hand corner for his second goal of the night and Sporting’s third.
Suddenly from being in complete control of the match City were somehow 3-1 behind.
It was a test of our resolve but Guardiola’s troops sought to reassert control and Bernardo almost carved open an opportunity on 65 minutes only to be denied in the box.
The skipper appealed for a penalty for handball by Ousmane Diomande and after a VAR check referee Daniel Siebert pointed to the spot.
Haaland stepped up and struck his spot kick with power but saw his effort ricochet over off the bar.
Foden then saw a fine free kick drift just wide as City sought that all important route back into the contest before Gyokeres then spurned the chance to notch his hat-trick.
Referee Sibert then took centre stage at the other end, awarding Sporting an 80th minute penalty after ruling that Nunes had pulled the short of substitute Geny.
Gyokeres made no mistake this time, firing home to seal his hat-trick and round off a hugely disappointing night.
Teams
SPORTING CP: Israel, Quenda (Quaresma 85), Reis (Braganca 74), Diomande, Debast, Araujo (Catamo 74), Hjulmand (C), Morita (St. Juste 74), Trincao, Goncalves, Gyokeres
Subs: Kovacevic, Pinto, Edwards, Harder, Fresneda, Esgaio, Simoes
CITY: Ederson, Lewis, Simpson-Pusey, Akanji, Gvardiol, Kovacic (De Bruyne 85), Bernardo (C) (Gundogan 77), Savinho (Doku 77), Foden, Nunes, Haaland
Subs: Ortega Moreno, Carson, Walker, Ake, Wright, O’Reilly, McAtee, Wilson-Esbrand
Pep’s reaction
“Congratulations to Sporting Lisbon for the game.
“We had a fantastic first half, now we are struggling to score. We create and concede when the opponents don’t do much.
“The first half was really good, we scored a goal, but every pass, the simple things we missed sometimes.
“It can happen. After the third and the fourth we have to avoid it. Emotionally we were not stable enough and in this competition you have to be stable. At 2-1, many things can happen. We have to be emotionally more stable.”
BERNARDO reaction
“It’s disappointing because we’re a bit in a dark place right now. Everything looks to be going in the wrong way.
“Even when we are playing well we don’t score our chances and we concede too easily. We definitely need to look inside and check what we’re not doing well. And we need to get better very quickly otherwise it will be very difficult to come back from these losses.
“It’s football. It’s difficult to find reasons for what is happening to us. I don’t remember in seven-and-a-half seasons this team losing three games in a row. It just looks like this team is going the wrong way now.
“The good thing is even though we have lost these three games we are still in a good position especially in the Premier League. After losing three games we are still in the main competitions fighting for everything. But we need to better, obviously.”
What it means
City slip down to sixth in the Champions League table.
We have seven points from four games at what is the halfway stage of our league programme.
What’s next
City return to Premier League action on Saturday and face another lengthy road trip this time away to Brighton and Hove Albion.
Kick-off at the AMEX Stadium, for what will be our last game before the November international break, gets underway at 17.30pm (UK).
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