Chelsea boss Jose Mourinho has warned his players that they cannot afford any more lapses in concentration ahead of their clash with title rivals Arsenal on Monday night.
Mourinho has been frustrated by the poor form of his strikers and defenders this season as they have shown a tendency to switch off in games.
"If we cannot improve our efficiency in front of the goal, we have to improve in the other end," Mourinho told reporters. "We have to improve when we lose possession of the ball. That's obvious.
"We cannot just let the players hide behind the fact that we are not scoring enough goals and wait for that to happen.
"We cannot play for that. People need to change their brains a little bit more. To be a team to play very good football is an important step. To be a team that plays very good football and wins lots of matches is a more difficult step."
Chelsea are currently one point behind third-placed Arsenal in the Premier League table.
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