Diego Simeone confirmed Joao Felix's injury is not serious and said he expects a great season from Diego Costa.
Joao Felix was withdrawn after less than half an hour of his Atleti debut against Numancia last weekend after hurting his hip.
The Portugal international then played no part in Atletico's International Champions Cup game against Guadalajara.
Simeone indicated Joao Felix, Antoine Griezmann's replacement, could recover in time to face Real Madrid.
"He's a little hurt. It's an annoying blow, but we need it to be fine," Simeone said. "He trained in the morning without problems. I imagine tomorrow he will play for a while or start from the beginning."
Costa struggled for form last season with the Brazil-born Spain international only scoring two LaLiga goals.
Atletico has added Ivan Saponjic – who like Joao Felix has joined from Benfica – to boost its forward options but Simeone still has faith in Costa.
"Diego heard me speak in times of difficulty," Simeone said. "I don't change a comma in everything I think. I am convinced that it will be a great season for him and his team-mates."
The MetLife Stadium in New Jersey will host Saturday's historic clash, with Saul Niguez excited to take on Madrid.
"Although it is a friendly match, it is a derby. It is always special, it is the first that is played outside Europe, it makes us very excited to compete tomorrow," he said. "The really important thing is to prepare for the first official match, but we are going to play as if it were an official match, as if it were a final, because every time you wear the shirt of Atletico Madrid it is to give everything."