Chelsea boss Maurizio Sarri is demanding greater concentration from his players ahead of facing Arsenal today.

The accusation was that his players have occasionally become complacent after taking a lead in games and the message in training this week has centred on their need to "kill" opponents when they have the chance.

"I know very well that we need to improve a lot," Sarri said. "We need to improve from the tactical point of view and mentally. We had problems with reactions to difficulties in the beginning and now we react very well to a difficulty.

"Now we have to show we can react from a positive situation. In the last matches, when we scored, we lowered the application and attention. So now we have to work just to avoid this.

"We were superficial I think (against Newcastle) because we thought the match was won. Being superficial is one of the biggest problems a team can have, so we have to counter the superficiality.

"If you are winning 1-0, you cannot think that the match is easy. So you have to kill the match. Then you have to manage the match.

"The players know very well my opinion. I told them very often my feeling, sometimes, after the goal was that we were sometimes superficial. They know very well the situation, I think."