Philippe Mexes admits AC Milan's preseason form hasn't been good enough.
Milan have conceded eight goals in two games on tour of the US.
"There are so many new players, we have to do better," Mexes said.
"Now the goal is to be ready for August 31. We must wake up, we have to regroup to return Milan to its place.
"I think it is mostly a matter of attention, because to concede four goals in 30 minutes [against Manchester City] and play the way we played is not normal.
"We have to improve from this point of view and stand up. Losing 5-1, although in a friendly, is always disappointing, especially for a team like Milan.
"Fans want to see a competitive team, we did not play well enough."
