The 21-year-old Brazil international has started all four of the Blues' matches so far this season, scoring in their opening Barclays Premier League fixture at home to Hull.
Former Internacional man Oscar is looking to build on an impressive first season in English football and believes he will benefit from the managerial prowess of Mourinho.
"It's been great to work with Jose Mourinho," he told the club's official magazine, Chelsea FC.
"He is one of the best coaches in the world. We have seen he has already had a lot of success at Chelsea and I am just really happy to have the opportunity to work with him.
"You can already see the influence he has had on us during the first few games and I hope the team will be able to continue to grow under him as I will also be able to grow as a player.
"As early as pre-season we could see the belief with which he works. We could see the confidence he has with us as players but also the confidence within his own work. It is clear to us that he is a great coach."
Oscar, who is likely to feature in Brazil's upcoming friendlies against Australia and Portugal, played in Chelsea's 2-1 Europa League final success against Benfica at the end of last season and has the taste for more success this year, with personal targets also in place.
"It's all down to confidence," he said.
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