The £21 million arrival from Barcelona opened his account after less than 20 minutes, before assisting Diego Costa as the champions held off a resilient West Brom side to win 3-2 at the Hawthorns on Sunday.
“He wasn’t quite Maradona but he was close,” Mourinho told Chelsea TV. “He’s a very good player. There is always a question mark because of how many top players come to England and don’t perform immediately.
“We have examples in our club and there are lots of examples at other clubs, so it’s very nice for him to come and straight away perform the way he did.
“I expected him to perform like that because he had a good pre-season, and he played three competitive matches. He came with minutes, with intensity, so it was not a question of intensity and condition, it was a question of understanding.
“We worked tactically every day since he arrived for him to try to understand the team and for the team to try to understand what he wants and needs. It was a very good performance.”