Chelsea manager Jose Mourinho is eager to rebuild Nemanja Matic's confidence after a slow start to the season.
Matic, a key part of his side's Premier League title success in 2014-15, has endured a difficult campaign thus far.
He was substituted after coming on against Southampton and started on the bench against Aston Villa on Saturday – days after being sent off for Serbia.
"Confidence is fundamental. Matic lost an easy pass when he came on [against Villa] and the first reaction he had was to show disappointment," he said.
"When you are full of confidence you don't show disappointment. You make a mistake, you know that you’re not going to make another mistake after.
"So [be] calm, let’s go step by step."
Matic came on for Ruben Loftus-Cheek in Chelsea's much-needed 2-0 victory against Villa.
"I think he [Loftus-Cheek] has to look to the intensity and the defensive tactical work that people like Ramires, [Cesc] Fabregas did and he didn't," he said.
"And try just to compare himself with others and understand why I didn’t keep him in the game for 90 minutes."
