What did you make of City's performance against Lyon?
Fekir, who was strongly linked with a move to City's Premier League rivals Liverpool in the close season, then made it 2-0 to the French side in the 43rd minute, bursting clear and beating Ederson with a low drive after Fernandinho had given up possession in midfield.
"The reality is Pep was not here and we lost the game", said the Spaniard.
"It is disappointing. We are usually strong at home".
Arteta admitted he is surprised that Real Madrid haven't retained their status as favourites after winning three consecutive Champions League titles and with the final to be played in the Spanish capital this season.
Although Guardiola's role will be heavily restricted on Wednesday, Arteta confirmed that City's build-up to their Group F opener had been no different than usual.
The Champions League anthem was again booed by the crowd - reflecting to ongoing bitterness over UEFA sanctioning the club for breaching spending rules - and the team often fails to sell out group-stage games.
Defeat is City's fourth in a row in the Champions League, but Arteta said they were "well prepared" for the match.