The 28-year-old, who joined Inter Milan in January from Lazio, admits that while he has not found his best form for the club, he is confident of improving before the end of the season.
"Me starting for Brazil at the World Cup? I haven't managed to express my full potential yet as I've had some physical problems," he told Inter's official website.
"I really want to go to the World Cup and not just as a reserve. I want to go into the tournament in good form because it means a lot to me.
"Playing regularly I can reach my physical peak, but first of all we have to turn things around and get them going our way again."
Hernanes has won 23 caps for Brazil, scoring twice in the process.