Lucas was impressed by Old Trafford and the supporters after making a brief cameo appearance as a substitute in Brazil's 3-1 Olympic win against Belarus at the weekend.
"The fans screaming my name was a very pleasant surprise," he told Superesportes.
"I was glad. I tried to do something in the little time I had to play but the most important thing is that we won and we qualified. The stadium is wonderful with a fantastic structure. For me, it was very cool.
"At the moment, I am a player from Sao Paulo and I'm focused on the Olympics."