Chelsea manager Jose Mourinho has claimed that Diego Costa is lacking in confidence this season.

Mourinho had a touchline bust-up with Costa last month, but the Portuguese coach praised the controversial striker following his performance in Wednesday night's 2-0 win over Porto.

Costa did not score, but he impressed his manager as the team sealed their place in the last 16 of the Champions League.

"It's clear but what is also clear is his effort, commitment and great movement, which is something he hasn't had in the last couple of months," Mourinho told reporters. "The first goal was obviously an own goal but his movement was great when the pass arrived. Last season he would have scored immediately but this season he couldn't.

"With the second chance when he faced the keeper on his own, you could immediately feel the lack of confidence because the first thing he did was not attack the goal but look to the linesman. When he did that he lost an important second and his last touch on the ball was not the best.

"He could have scored two or three goals. There is a lack of confidence, clearly, but his attitude was very good and his movement was much better, so goals are coming."

Costa has scored just four goals in all competitions this season.