Manager Philippe Clement has made it clear he's rationing the playing minutes for his star 22-year-old Australian striker to keep him fresh, but it still felt somewhat of a defeatist decision to leave his main weapon on the bench during their glamour third-round tie at the Etihad Stadium which ended with a 5-0 drubbing.
By the time Clement deigned to bring on Toure with 20 minutes left, Championship side Norwich were already 4-0 down, with City teenager Floyd Samba having stolen the limelight with two goals on debut.
Toure then gave glimpses of what the Canaries had been missing as he looked sharp, incisive and even found the net from Anthony Musaba's neat pass only to get penalised for a narrow offside.
Toure had netted his fifth goal in seven games after just 52 seconds at the weekend against Middlesbrough, but the man who's struck in the first two minutes of matches three times already this season wasn't given the chance to get Norwich off to a lightning start this time.
Instead, 17-year-old Samba stole the show for City, not only scoring his brace but also having a hand in Rayan Cherki's goal as they ran riot against Clement's weakened selection.
Winger Allan Elias, signed for Stg 34million ($A64 million) from Palmeiras last month, also marked his first appearance with a splendid individual goal while there was a fifth in the 90th minute from another youngster, sub Ryan McAidoo.
It couldn't have been easier for Enzo Maresca's side, who will now face Manchester United's conquerors Brighton in the next round.
While Maresca made 10 changes from the team that won at United on Sunday, with Erling Haaland not even on the bench, Norwich themselves made nine changes from their weekend loss to Middlesbrough, indicating where the tie lay in Clement's priorities.
Samba was at the heart of the two goals, in the space of three minutes around the half-hour mark, that effectively ended the match as a contest.
First, he glanced in a far-post header from Nico O'Reilly's cross, then skilfully released Stg86million ($A162 million) man Ayyoub Bouaddi, who powered forward and picked out French international Cherki to finish from the edge of the area.
Norwich imploded after the break, woeful defending enabling Rayan Ait-Nouri to set up Samba for a neatly taken curler, and after Toure's late strike was disallowed, 18-year-old McAidoo made it five in the 90th minute.
