Carlo Ancelotti has said he was worried about Real Madrid's level of performance in their 3-1 home defeat to AC Milan in the Champions League on Tuesday.
The result marked the first time in three years that they have suffered back-to-back defeats in all competitions, having been hammered 4-0 by Barcelona at the Bernabeu last time out.
Following the match, Real Madrid are 17th in the Champions League table – just three points off dropping out of the play-off positions – with Wednesday's games to come.
"We have to be concerned, the team is not playing well," Ancelotti told a press conference on Tuesday.
"The team is not compact, we need to be more compact, more organised, we've conceded a lot of goals ... The team is not well organised on the pitch and we need to work on this.
"We have to focus on what we have today, which is a team that is not at its best, and get back to our level so we can fight for all competitions."
Real Madrid have conceded nine goals in their last three matches, while a Vinicius Junior penalty on Tuesday was their only goal in their last two. Players such as Aurelien Tchouameni and Kylian Mbappe, meanwhile, were booed by fans.
"It is not an issue of motivation or attitude, it's a collective thing that we need to fix quickly," said Ancelotti.
"On the pitch, something is missing and we have not been able to show our best version. We have to fix this, but the nights are going to be very long and we have to recover the solidity that we are lacking.
"That's the problem above all, we've conceded too many goals for a team that is built on solidity.
"We have to accept criticism and accept reality. We want to do better because it's very difficult to get to the end of the season like this. We have to defend better and we have to look for solutions, without going crazy after drastic changes.
"It's good that the players are down like I am. We can all think about how to improve our version. We are confident that this team will improve." (Reporting by Fernando Kallas; Editing by Ken Ferris)