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

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

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 half-time 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 December 15.

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

"We had a fantastic first half, now we are struggling to score. We create and concede when the opponents don't do much," Guardiola said. "At 2-1 down, many things can happen. Emotionally, we were not stable enough – and in this competition, you have to be stable."

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's heaviest defeat since 2020 meant, for only the second time in the Guardiola era, they had suffered three consecutive losses in a single season.

Sporting, meanwhile, have 10 points from four Champions League games as Amorim leaves them in rude health. (AFP)