The midfielder has found himself largely sidelined this season, leading to talk of a January exit.
But ahead of today's clash at Crystal Palace, Amorim said: "Yeah, but this is a team sport.
"You talk a lot of about Kobbie, I have more players in my squad that want to be in the World Cup, so it's a little bit unfair. I put Kobbie (in on Monday against Everton) because he's really good near the box, to have a guy like Bruno and him, they can find spaces near the box and score goals.
"So that was my idea. So, I will use Kobbie and the rest of them to try for the team to win. So, I'm not just focused on one individual.
"I want to help all my players and I know how special it is for a player to play World Cup. My job is to win as a team and to focus as a team. So, Kobbie Mainoo is in the same situation as the other guys. If I feel that is the best thing to win the game, I will do it. So that's it."
He continued: "I see him as a starter like the other guys. I just have to make a choice and then in the end, it’s not been Kobbie.
"But in the future, I don't know. Again, I always think the same thing with Casemiro. Casemiro was not playing and then he plays. I just want to win games. I don't care who is playing. I just want to win games."