Joao made a wonderful start to the season, and he earned two senior international call-ups for Portugal due to his good form.
However, since taking such acclaim, the youngster’s form has dropped off and Carvalhal suggests that he got carried away.
“It’s good for Lucas’s confidence he scored,” Carvalhal said.
“I’m not magic. I said we needed to manage Lucas very well and put him in the correct environment to score goals.
“I tried to put expectations down about Lucas but the environment was more strong than my words. People started to have a lot of expectations of him.
“Lucas scored against Arsenal and went to the national team. Everyone said he must play in the first 11 because he’s the best striker in the whole world.
“He’s a boy and lives a little in the clouds. The reality is we maybe missed Lucas for two months. We lost him for some time. It is a lesson to all of us.”
Joao scored his first goal for 14 matches in Wednesday’s 4-0 win against Brentford on Saturday afternoon.
His strike sealed Wednesday's triumph, and although it may not have been crucial to the team it certainly will have boosted the 22-year-old’s confidence.
There are still high hopes for Joao’s future at Hillsborough as he has had a productive first campaign in English football - despite his recent drought.
Joao has netted six Championship goals in 10 starts and 18 substitute appearances, and he may well play a more prominent role in Carvalhal’s side next season.