Manchester City manager Manuel Pellegrini says his side must improve their concentration at the back but denied they are showing defensive weaknesses similar to last season.
City's 100 per cent start to the Premier League campaign came to an end against West Ham on Saturday, with Victor Moses and Diafra Sakho on target in a clinical performance from the visitors at the Etihad Stadium.
While Kevin De Bruyne pulled one back, a City side shorn of injured captain Vincent Kompany saw their lead cut to three points after also being beaten by Juventus in their Champions League opener in midweek.
Having surrendered the title to Chelsea last season, Pellegrini warned of the need to improve defensively but refused to press the panic button.
"I don't want to compare one season with the other because we are just starting this season," said the Chilean.
"I think that in the two last games [against Juve and West Ham] we didn't play with the concentration and the intensity that we need in defending so we conceded against Juventus - they shot twice at our goal and they scored two goals.
"[This match] was the same - one shot from outside the box and one from a corner was the offensive volume that West Ham had in the whole of the game.
"We must be more concentrated in specific balls because two balls decided the result."