Roberto Mancini has suggested that Manchester City's defensive problems have come as a result of their fragmented pre-season.
City head into Sunday's encounter with Arsenal still searching for the form that saw them crowned Premier League champions last season.
The biggest issue has been at the back, with City suddenly looking vulnerable after having the top flight's best defensive record last term.
Including the Community Shield, the Blues have conceded 11 goals in six games so far this season, culminating in the three at the Bernabeu on Tuesday that cost them a famous UEFA Champions League away win over Real Madrid.
It took City 13 games to reach that number last season, and Mancini has pinpointed what he believes to be the reason for that change.
"For two years we were the best defence in the Premier League," he said.
"This year we have been average.
"Probably the big problem was we didn't get to work properly in pre-season. Since then we lost some players and have had an international break.
"But if we are going to improve, we need to work."
Joleon Lescott paid the price in midweek as Serbian teenager Matija Nastasic came in at centre-back, but Mancini insists it was not a significant decision.
"No," he said. "We have played six games this season and all the players have played two or three.
"The problem was because we started pre-season in a different moment.
"Joleon came back very late. He is an important player for us but we have 23 good players. Sometimes I can change them."
Mancini accepts Sunday's game will offer a decent guide to his team's present situation, with Arsenal in decent form and summer signings Santi Cazorla and Lukas Podolski particularly impressive.
Mancini dispatched trusted reserve-team coach Attilio Lombardo to Anfield to run the rule over the Gunners three weeks ago.
"Arsenal are very strong on the counter-attack," said Mancini.
"I watched the game against Liverpool on TV and they played really well.
"They have two important players, Cazorla and Podolski, who are very good and Olivier Giroud maybe. He didn't score but he is a good player.
"We should pay attention because their counter-attack will be very strong."