The 25-year-old scoring a brace inside eight minutes, the first of which came after only 57 seconds, and Mourinho hopes he can take that form into the new season.
"What can we expect? I expect Diego and Diego is a team player who works hard, he's not just about goals," said the Blues boss to chelseafc.com. "It's about his defensive work, mentality and ambition. This is the player we bought and we were waiting for since last season. This is why we didn't buy a striker in the winter market. We were waiting for him, we have him and hopefully everything goes well.
"He looks adapted to the team, and the Premier League, not just Chelsea, should be happy. Sometimes we lose important players going to other countries and sometimes we bring new top players here.
"You can consider that [a bargain] because the market is crazy and the values are very high. For a striker like him, a champion in Spain, a Champions League finalist, a 25-year-old, we consider the price was very much in our favour."
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