Brazilian ace Willian was left out of the starting line-up for Monday's impressive 3-1 win over Burnley, only coming off the bench late on.
Willian, who arrived at Chelsea last summer from Shahktar Donetsk, was a regular for Mourinho last season, but he faces increased competition for places this season following the arrival of Cesc Fabregas.
The 26-year-old scored four goals last season and he feels he needs to be more clinical in front of goal if he is to win his place back in the starting XI.
"I think I have to score more goals, to play better and just be better," said Willian.
"Last season I did good, not bad, but I want more."
Willian also admitted Chelsea need to win some trophies this season after ending last season without any silverware.
“New players have come in and this season we have to win some titles," added Willian.