Viktor Gyokeres's hat-trick fired Sporting Lisbon to a stunning 4-1 rout of Manchester City in the Champions League as Ruben Amorim showed why Manchester United were so keen to lure him to Old Trafford.

Sporting manager Amorim has accepted United's offer to replace Erik ten Hag and will officially take charge of the troubled Premier League club on 11 November.

Regarded as one of Europe's brightest young managerial minds, the 39-year-old delivered a tantalising glimpse of his acumen as Sporting exposed injury-hit City's defensive weaknesses.

Phil Foden put City ahead in the opening moments at the Jose Alvalade stadium, but the visitors wasted a string of chances to increase their lead and Sporting made them pay.

Gyokeres equalised before halftime and Maximiliano Araujo bagged Sporting's second after the break before Gyokeres's penalty capped their incredible fightback with two penalties.

Erling Haaland squandered a chance to give City a second half lifeline when his penalty hit the bar.

Amorim said United fans might think "the new Alex Ferguson has arrived" if his team beat City.

After the turbulent end to Ten Hag's reign – he was sacked in October with United languishing in the bottom half of the table – Amorim clearly faces a huge task to restore the club to the glory they enjoyed in the Ferguson era.

Comparisons with United's legendary former boss should be shelved for now, but Sporting's spirited victory will have fans counting down the days until his arrival.

Amorim, who led Sporting to two Portuguese titles in four years, is set to take charge of his first United game at Ipswich on November 24.

Pep Guardiola will get his chance for revenge in Amorim's first Manchester derby at the Etihad Stadium on 15 December.

But Guardiola has plenty to work on before then as he looks for solutions to City's unexpected three-game losing streak.

Premier League champions City suffered a first top-flight defeat of the season against Bournemouth on Saturday, three days after losing to Tottenham in the League Cup.

Amid the absences of Rodri, Jack Grealish, Ruben Dias, John Stones and Oscar Bobb, City have lost their momentum in dramatic fashion.

Their first defeat in four games in this season's Champions League shouldn't be fatal to their European ambitions, but Guardiola will be desperate for a positive reaction at Brighton on Saturday.

CITY STUNNED

Sporting have 10 points from four Champions League games as Amorim leaves them in rude health.

In the last home game of Amorim's reign, City looked like puncturing the emotional farewell when Foden struck in the fourth minute.

Sporting carelessly conceded possession to Foden, who advanced into the penalty area before drilling a low shot past Franco Israel's weak attempted save.

But Israel redeemed himself when he repelled Haaland's drive before the City striker's looping header was cleared off the line by Gyokeres.

Haaland tested the over-worked Israel with a volley before Bernardo Silva fired just wide.

Guardiola's men had kept clean-sheets in each of their first three Champions League games, but they were breached completely against the run of play in the 38th minute.

City centre-back Jahmai Simpson-Pusey was making his first start for the club and the raw 19-year-old was exposed by Gyokeres, who accelerated past him to reach Geovany Quenda's pass and clip a predatory finish into the far corner.

Amorim's celebration was relatively brief as he focused on issuing tactical instructions to a trio of Sporting players on the touchline.

If Amorim's words of wisdom had identified a City weakness, he was rewarded in an astonishing start to the second half.

Just 20 seconds after the interval, Araujo surged through for a clinical finish that whistled under Ederson.

Three minutes later, City were breached again when Josko Gvardiol's rash foul on Trincao conceded a penalty that Gyokeres slammed past Ederson.

Ousmane Diomande blocked Silva's shot with his arm, conceding a penalty that Haaland smashed against the bar.

It was Amorim's night and Gyokeres put the exclamation point on it in the 80th minute with an ice-cool penalty after Nunes's foul on Geny Catamo. (AFP)