Graham Potter described Chelsea’s performance at Manchester City as “a step forward” despite the 2-0 defeat.
Two City goals in the space of five minutes early in the second half sent Potter’s side out of the Carabao Cup.
Riyad Mahrez’s free-kick broke the deadlock before Julian Alvarez doubled the home side’s lead by tucking away the loose ball after Mahrez’s shot had been saved by keeper Edouard Mendy.
Blues youngster Lewis Hall, 18, made his second senior appearance – and was twice denied at point-blank range by keeper Stefan Ortega.
Mason Mount went close to pulling a goal back when he fired wide late on.
And Chelsea had a goal disallowed in the final moments after a comedy of errors in the City box.
Ortega fumbled a cross, Sergio Gomez headed against his own bar and the ball fell to Christian Pulisic, whose shot was diverted into his own net by former Chelsea defender Nathan Ake – but Pulisic was offside.
The defeat was Chelsea’s third in their past four matches.
But boss Potter insisted: “I thought there were quite a few positives.
“Obviously we’re disappointed with the result, but in terms of how we played, we created some good chances and there was a better structure and a better performance level.
“The team looked closer to what we want it to look like. The boys had create courage and they tried against what is obviously a top team.
“Overall, I think a step forward for us.”
Chelsea: Mendy, Chalobah (Azpilicueta 69), Koulibaly, Cucurella, Loftus-Cheek, Zakaria (Gallagher 68), Kovacic, Hall (Havertz 75), Ziyech (Sterling 68), Broja (Mount 68), Pulisic.
Subs not used: Bettinelli, Silva, Hutchinson, Sterling, Aubameyang.