"The ideal scenario is to have a full stadium every time and being behind the team like insane but we know sometimes it doesn't happen".
Whether Guardiola's absence from the dugout was behind City's ragged first-half display is hard to ascertain, but the team produced their worst performance for months while he was not standing in his technical area.
When a pass by the Brazilian midfielder was intercepted around the halfway line, Lyon charged forward.
City's troubles deepened when Fernandinho was caught in possession again. The reality is Pep wasn't here and we lost the game.
"We started slow and we were not consistent in the way we were trying to play".
The Manchester club faces Cardiff City next on Saturday.
"We didn't feel the flow around the team", said Arteta.
The 36-year-old said: "I am surprised when you have a team that won it three times in a row but that means we are doing things really well".
There are reports coming in that up to half of the seats were left empty.
But the improvement wasn't sufficient.
It could even have been 3-0 when Memphis Depay hit the post on the hour after a magnificent through ball from Tanguy Ndombele, but after that let-off City earned themselves a lifeline through Bernardo Silva, who produced a smart finish after a superb jinking run from substitute Leroy Sane.
But the attacking threat was too patchy from a City side that won the Premier League with a record 100 points only four months ago, and are widely seen as one of the big favorites in this season's Champions League.
The near miss sparked City back into life with two neat moves leading to Delph getting shots away from the edge of the area, the second of which was well dealt with by Lopes down to his right.
"It is disappointing. We are usually strong at home".
The hunger is this group is incredible."said Arteta, but he changed his tack when asked who he views as favourites".