"I was able to cover a lot of ground against Japan and I think I took my opportunity [in the team] rather well," Coutinho is quoted as saying on Liverpool's official website.
"Everything has to be for the team. Brazil have a lot of quality players and I have to work very hard to earn my place and remain in the squad.
"The team as a whole had a great game. We managed to get on the ball and engage Japan from the first minute. And then we have an inspiration in Neymar."
Barcelona forward Neymar scored all four goals for Brazil to take his international tally up to 40 goals in 58 games.